Appraisal Quick Reference Guide

Jewelry of value should have its own documentation. Professional appraisers may charge more for a report, but it is worth the expense to know what you are buying, to know what you own, or to get what you own insured. Fees vary among professionals as do their qualifications. You should research the appraiser on your own before having the work done.

Many types of appraisals exist including insurance documents, point of sale documents, donation appraisals, and estate appraisals. These all serve different functions, so be sure to get the proper documentation for the job.

The most common insurance appraisal is a replacement type policy. Basically, this policy protects for most perils and allows for the item to be replaced with a similar item of jewelry. Another type of coverage is the agreed value policy where the settlement is for cash and not for replacement of the jewelry. Generally, these policies would carry a higher premium. All insurance matters should be discussed with your agent to determine what coverage is available and what is best for you.

A proper professional appraisal should have the following elements present: 1) Description. A full description of the item. 2) Photograph. While not required, it makes it much easier to identify and replace the item once it no longer exists. 3) Value. A value that is not inflated, nor undervalued, as these would be detrimental to the client and could greatly affect premiums and settlements. 4) Taxes. No rules exist and tax rates vary even from county to county. The appraisal document should be clear as to whether taxes are or are not included in the value. 5) Plotting or Laser inscription. Some easy form of identification should be present for diamonds of significant size or value. Some appraisers will plot if the diamond is above one carat, but no standards exist. Nor are there any requirements for plotting by most major insurance companies. In lieu of a plot, a laser inscription may be present on the girdle of the diamond. 6) Treatment information. According to the Federal Trade Commission in the Unites States, almost all treatments need to be disclosed to the consumer. If the seller has not done this, it may be in violation of the codes. Appraisals should also contain this important information.

Finding the right appraiser requires an investigation of his or her qualifications. Jewelry appraising, unlike real estate appraising, is not a licensed profession. Some appraisers may belong to professional associations. It is also recommended that the appraiser have gemological credentials from a recognized trade school.

The single most important caveat regarding appraisals is the fictitious inflated value appraisal. A simple rule to follow is that if it is too good to be true, it probably is. Misrepresentation of value is a major problem in the jewelry industry.

Appraisals

Information on this education section has been prepared by Gemworld International, Inc., an authority in the jewelry industry providing unbiased information since 1982.

Introduction

Buying jewelry is a joyous occasion. Important jewelry should have its own documentation containing all the information about that jewelry. When it comes to finding an appraiser, it is much the same as finding a doctor. There are different levels of expertise and specialties. There are different fees that appraisers charge. The most expensive appraiser is not necessarily the best, nor is the least expensive necessarily the worst.

However, with appraisals, you generally get what you pay for. The short "one-line" appraisal with a value is not nearly enough information to describe adequately an expensive engagement ring. Yet, these still exist. The danger in using an inadequate appraisal is that you may buy an item for more than it is worth or sell it for less than it is worth.  Moreover, should there be a loss, the insurance company would have great leverage in the replacement process if you have a low-quality appraisal. For example, a basic one-line description of a diamond solitaire engagement ring stating only the size, color and clarity of the diamond, says nothing about the cut or proportions. Suppose the client had a diamond with very good proportions. This inadequate report would allow the insurance company to replace the diamond with one that had only a fair cut, and the client would have no recourse. That is why it is so important to learn as much as you can about appraisals and what to look for before contracting for the work to be done and before submitting the appraisal for insurance coverage.

What follows here is a primer on appraisals. You will learn what to look for in an appraisal, what types of appraisals exist, and what types of insurance coverage are available. You will also learn about professional affiliations, methodologies used to determine value, and some caveats when buying jewelry and relying on appraisals.

Types of Appraisals

These two appraisals are for a diamond engagement ring. The one above is a professionally prepared document. The one below is not.

Jewelry appraisals are usually done with the intent to purchase insurance. However, several other types of appraisals may be desired depending on the need. The following list covers the main types of appraisals. This information is not intended to offer insurance advice in any way. You should contact your insurance agent for any specific questions or advice. 

Insurance Document

An insurance appraisal is required when an item of jewelry is to be scheduled separately on an insurance policy. Standard coverage might include some aggregate allowance for jewelry. However, these limits are generally low and may not cover all perils. A separate insurance rider on any single item of jewelry will generally cover perils including theft, loss, mysterious disappearance, fire, etc. You should refer to the actual policy for explanation of coverage.

Point of Sale Document

A point of sale document is similar to an insurance document in that a retail value is provided so that the client can purchase insurance. However, this document may be provided by the actual seller of the item of jewelry and it will report the actual selling price. In this type of appraisal, the seller is disclosing his/her role in the transaction. This type of document is valid and acceptable for obtaining insurance. The seller usually has an accurate description of the necessary information like the weights of the gemstones. The selling price is often the best price to use for obtaining insurance. 

Donation

When an item of jewelry is being donated to any charitable organization, an appraisal is required. The value to be used for tax reporting is most commonly the fair market value. This is defined as the price that a willing buyer and willing seller would agree upon. (See the section on Estate appraisals for a full definition.) An example of fair market value might be the price that an item sells for at a local auction. Rarely is this price a full retail price. Depending on the condition of the item and the desirability of the item, the fair market value might be as low as “scrap” value or rarely, as high as retail value.

All property valued greater than $5,000 that is being donated must be accompanied by a written appraisal. The appraiser must be qualified (there are specific rules regarding this) and must fill out and sign the taxpayer form number 8283 Non-Cash Charitable Contributions that will be submitted along with the person’s federal tax return.

Estate

When a death occurs, the heirs may be requested to obtain an estate appraisal. Here again, the value used would be fair market value. The full definition that is used in federal guidelines for estate tax purposes can be found in publications like Black’s Law Dictionary, which defines fair market value as follows:

“The amount at which property would change hands between a willing buyer and a willing seller, neither being under any compulsion to buy or sell and both having reasonable knowledge of the relevant facts. By fair market value is meant the price in cash, or its equivalent, that the property would have brought at the time of taking, considering its highest and most profitable use, if then offered for sale in the open market, in competition with other similar properties at or near the location of the property taken, with a reasonable time allowed to find a purchaser.”

Elements of the Report

While many insurance companies will not follow specific guidelines for what should be in appraisals, they are starting to pay closer attention to jewelry of higher value. Regardless of value, here are some guidelines of what to expect on a professional appraisal report.

Description

A full description of the item of jewelry should be included. Although a photo should also be present, the description should be adequate enough to create a mental picture of the item of jewelry. The photo, when present can add the details.

Photo

Although no rules exist regarding the requirement for a photograph of the jewelry, in the digital age of photography, there is no reason not to have a photo present. The photo can now be printed directly on the appraisal report.

Value

It goes without saying that an appraisal without a value is not an appraisal. Some types of documents like identification or certification only reports would not have a value, but again, these are not appraisals to be used for insurance. These types of reports may be supplemental reports to the actual appraisal.

Taxes

Here again no rules exist for whether taxes should be included on an appraisal. Opinions vary. Some say that with all the different tax bases that exist not only from state to state but from county to county, that it is too difficult to list out taxes. Some clients do not even know their exact tax rate when asked. While most insurance companies do not have any rules for this, it is important that, whatever the appraiser chooses to do on the report,  it is clearly stated whether taxes are included or not.

Plotting

Plotting first began in the 1950s as a means of identifying a diamond. A plot is a diagram of the inclusions and surface blemishes that exist within or on a gemstone, primarily done for major diamonds. These markings are drawn onto a representative diagram of the diamond. Later, when lasers became popular, an inscription could be microscopically placed along the edge of the diamond, and this became another method for identification. Today, the laser inscription will often be used instead of a plot.

There are no specific rules regarding the necessity of plotting. Some appraisers plot, and others do not. Some appraisers have their own internal guidelines like plotting for all diamonds one carat or larger. Most insurance companies do not have guidelines and will accept appraisals with or without plots.

The Gemological Institute of America is the education arm of the jewelry industry. It also owns and operates a diamond grading laboratory. Diamonds that are 2.00 carats or larger receive a plot. On diamonds that are less than 2.00 carats, the client has the option to get a full report with a plot or to get a “Dossier” with no plot but with a laser inscription instead.

Treatment information

According to the Federal Trade Commission guidelines, almost all treatments need to be disclosed. The jewelry industry tends to be lax regarding disclosure of treatments but not always to be deceitful. For example, since nearly every ruby and sapphire has been heat treated to improve color, and this practice has existed for more than 100 years, jewelers tend simply to accept treatment as fact and do not disclose this information. However, the information should be given to the consumer.

On appraisals, this information is also helpful to have because it is a value factor. Treatment information can be provided on the report directly or as part of addendums that some appraisers use. Often, a generic discussion of treatments is sufficient as the understanding that most gems are treated in some fashion is a true statement. The lack of any treatment may increase the value, and that information should also be disclosed. (For a full discussion on treatments, see the education sections on diamonds and colored gems.)

Qualifications of the Appraiser

Jewelry appraising is not a licensed profession. That means that anyone can perform an appraisal, qualified or not. Some insurance companies are starting to look at high value items a bit closer, and if the appraiser does not have certain credentials, the report is rejected. However, the bulk of all appraisals today can still be performed by anyone.

Many jewelers perform appraisals, and some are credentialed while others are not. The lack of credentials does not infer a total lack of ability to perform the appraisal, nor does the existence of credentials infer expertise in this profession. Unlike real estate appraising where credentials and testing are required on an ongoing basis, jewelry appraisers are mostly self-policed. As a consumer, it is up to you to ask questions regarding the appraiser’s qualifications and ability.

Qualifications

To begin, an appraiser should have some gemological experience. However, remember that courses in gemology are to teach how to identify and evaluate gem materials but do not teach how to value or appraise. The valuation process is entirely different from gemological skills. The largest school for gemology is the Gemological Institute of America (GIA). Successful completion of its courses through correspondence or in-residence achieves the title of Graduate Gemologist(GG). Other smaller schools have also come into existence over the years. The International School of Gemology (ISG) is one such school. Overseas schools also exist. The most prominent of these offers a title of Fellow of the Gemological Association of Great Britain (FGA). The FGA title is regarded as equivalent to the GG title in the United States.

Organizations

Several appraisal organizations do exist to which appraisers may belong. Some have more stringent testing requirements than others. The prominent appraisal associations in the U.S. are listed here in alphabetical order. All that are listed except the NAJA are multi-disciplinary, meaning that they have other types of appraisers besides jewelry. The NAJA is jewelry only.

• American Society of Appraisers (ASA)
• Appraisers Association of America (AAA)
• International Society of Appraisers (ISA)
• National Association of Jewelry Appraisers (NAJA)

Methodologies Used to Obtain Value

When an item of jewelry is brought to an appraiser to establish a value, two methodologies may be used. They are the cost approach and the market data approach. The appraisal assignment and the details of the item itself will determine which method is used.

Cost approach

The cost approach is the most common method of appraising for insurance assignments. This method simply looks at all the components of the item of jewelry like the costs of gems, metal, labor, etc. Once the components are individually valued, they are added up, and a markup is applied to get to the retail replacement value. This method may not be used when trademarks or copyrights are present.  In that case the market data approach should be used.

Market Data Approach

With the market data approach, the item of jewelry is evaluated as a whole. For example, an item may have a trademark from a particular designer. Now, it is important to do market research in an effort to determine what that designer item of jewelry sells for in its typical market.

Some items like watches are clear examples of when market data is used as opposed to cost. One could never value a watch properly by adding up the components in the manufacturing process. Watches have a set market price with suggested retail values. They may be discounted at some stores, but the market data can usually be found for new watches.

Another example where market data is used is for assignments other than insurance. For example, in an estate assignment, the value needed is fair market value. The definition of this is stated previously, but because it involves valuing in the open market in venues like auctions, the cost approach will not work. The appraiser must research the market to determine what these items might sell for under the proper conditions to satisfy the definition.

Insurance Coverage

When a consumer takes the appraisal document and submits it for insurance coverage, more than one type of coverage exists. Insurance laws vary from state to state, so it is important to consult your insurance agent for a full explanation of coverage and benefits. However, this educational section will cover the basics of insurance coverage so you will know what to ask and what to expect in case of a loss.

Replacement Policy

In a replacement policy, which is the most common type of insurance, the premium is based on the anticipated retail replacement value of the item of jewelry. Usually, this value is for replacement of “similar kind and quality” meaning that you are made whole by replacement of the item as close to the original as possible. When trademarks or copyrights exist, the replacement should account for those, and the consumer should receive the same or comparable trademarked or copyrighted item of jewelry instead of a generic replacement.

When the appraiser sets a value, he or she should attempt to value the item considering all value factors like the aforementioned trademarks. When the final value is determined based on replacement in a typical retail store for that geographic location, the insurance company now has a value by which to charge a premium.

However, it is important to understand that the value used for this premium may not be what the insurance company ultimately pays out in case of a loss. Replacement policies are just that—they give the insurance company the right to replace the item of jewelry. Sometimes, this cost could be lower than the full retail price established by the appraiser. This is because the insurance company may have established relationships with jewelry suppliers for a lower price based on volume purchasing. Therefore, the retail price on the appraisal is the highest price that the insurance company is liable to pay out. See the cash settlement section below.

Agreed Value

An agreed value policy works different than a replacement type policy. The appraisal document does not change and will still reflect the full retail replacement value. However, in this case, should there be a loss, the insurance company will now issue a check for the full amount as stated and will not attempt to replace the item of jewelry.  Clients can go anywhere they would like for the replacement and may even choose not to replace the item or to purchase something completely different. Since the insurance company will not have the option of replacing the item at a discount, these types of policies generally will carry a higher premium. Note though that if the appraisal is proven to be fraudulent or an unrealistic value for the item, this may constitute fraud, and the insurance company would not be liable to pay.

Cash Settlement

In the case of a replacement policy, when there is a loss, the item of jewelry may not always be replaced for one reason or another. Perhaps the client no longer wants this item, or it is no longer available for replacement. In this case, the insurance company may negotiate a cash settlement. Remember, because this is not an agreed value policy, the insurance company does not necessarily have to pay out the full amount of coverage. That is only the upper limit of its obligation. The settlement offered will usually be the amount at which the company can actually replace the item based on quotes obtained from its suppliers and manufacturers. Again, remember that the insurance companies have great buying power, so this price may be lower than what you originally paid.

Caveats Regarding Appraisals

Inflated appraisals

A huge misconception exists that a high value on an appraisal is good for a consumer. Nothing could be further from the truth. When it comes to insurance replacement, remember that the insurance company will either replace the item at its cost or offer a cash settlement that is equal to its cost.

Suppose an item of jewelry is purchased for $10,000.00. The jewelry store understandably has made a profit on this item. The jeweler and/or appraiser gives an appraisal for $15,000.00, informing the client that the item is really worth “more than was paid.” Premiums are now set for the insurance based on $15,000.00. Now the item is lost. For this particular item, the insurance company can replace the item for $8,000.00. So, it will either be replaced for that or a cash settlement for that amount will be given. Did the inflated appraisal help or hurt the client? The client has paid an unnecessary higher premium. It is a fallacy that a higher appraisal will help you get a better settlement. It will only cost you more premiums.

So, what is an item worth? Generally, it is worth what you paid. If the store sells at a discount, it is still the price that the item is worth because it is the price they sell for all the time. A one time sale may be slightly different. In that case, the regular retail price may be more reflective of the value to use for insurance.

In an agreed value policy, an inflated appraisal may still not be to your advantage. Remember that with this type of policy, if fraud or misrepresentation such as an inflated appraisal appearing to exist occurs, the insurance company may have grounds to deny the claim or pay out a lesser amount. In either case, do you really want to experience an investigation over an inflated appraisal?

Misrepresentation

Another issue related to inflated value is misrepresentation. It is an unfortunate but common practice in some retail jewelry establishments to use so-called “independent laboratories” or “independent appraisers” to establish the grades of diamonds or gems and their values. We have seen color and clarity grades of diamonds inflated by one or more grades, and values that are anywhere from 50% too high to an unbelievable 10 times value. Yes, we have seen jewelry items that sold for $1,000.00 come with an appraisal for $10,000.00. The standard rule of life should apply here. “If it seems too good to be true, it probably is.” Do not fall for these traps.

Diamond Quick Reference Guide

The price of diamonds is ultimately determined based on the 4 C’s—color, clarity, cut, and carat weight.

Clarity:

Clarity is judged at ten power magnification. The clarity scale starts at Flawless (or Internally Flawless) which would have no imperfections under magnification. VVS1 and VVS2 are the next grades in the scale. These diamonds have minute inclusions that are very difficult to locate with magnification. VS1 and VS2 are the next grades, and these inclusions are very small and may be difficult to see under magnification. SI1 and SI2 clarity grades are easy to see with magnification. These are the most common grades sold. I1, I2 and I3 are diamonds with more inclusions, often visible without magnification. In the I2 and I3 grades, the beauty and/or durability might be compromised.

Cut:

Cut is actually the way the diamond is proportioned. Sometimes people confuse cut with shape which is an entirely different value factor. The cut is an assessment of all proportions and finish of the diamond including, but not limited to, the depth, table, girdle, cutlet, polish, and symmetry.

Carat:

Carat weight is simply the weight when placed on a scale. A diamond represented as .75 carat would weigh ¾ of a carat. Larger diamonds are more rare so for example, two diamonds weighing ½ carat each would cost much less than one diamond weighing 1.00 carat.

Light Performance:

Light performance is a new term that may be encountered. Some laboratories have some information on this as part of their service. The brilliance (white light), fire (colored light), and scintillation (sparkle) are the terms you may become more familiar with from these reports.

Fluorescence:

Fluorescence is a misunderstood phenomena of diamonds. About one third of all diamonds fluoresce in ultraviolet light. The most common color is blue. Fluorescence may actually improve the color of a diamond, so it should not immediately be thought of as a negative factor.

Diamonds:

Diamonds may be treated to improve their appearance. The most common methods for doing so are laser drilling, high temperature-high pressure (HTHP), irradiation, and clarity enhancement using a glass filler. Other methods exist. Most treatments can be detected and identified, but some are clearly a challenge in the industry.

Diamonds

Information on this education section has been prepared by Gemworld International, Inc., an authority in the jewelry industry providing unbiased information since 1982.

Introduction

Diamonds are the hardest of all gems and therefore can be polished to exquisite brilliance and can, under normal care, last a lifetime.

Mining and Distribution

When we think of diamonds, we often relate them to the name DeBeers. The DeBeers name has been associated with diamonds since their modern day discovery. The company, based in South Africa with headquarters in London, quickly became the largest distributor of diamonds and soon thereafter was considered a monopoly, controlling more than 80% of the world supply of diamonds. A distribution method was set up whereby “sight holders” were invited to buy boxes of diamond rough. This division of DeBeers is known as the DTC or Diamond Trading Company.

The way the system works is that these sightholders (clients) are invited to buy diamond rough usually ten times per year. They do not get to view the diamond rough prior to purchasing. The boxes are sealed and the buyers do not know what the mix will be like. The DTC has a good idea what sizes and qualities the buyer needs so they do try to offer that selection. However, the price is set and non-negotiable. When the DTC decided to raise prices, the sightholders had to accept the new price. While this system seems unfair, it did work well overall and this method of distribution helped create even greater demand for diamonds worldwide. People knew that diamond prices would continue to rise over time because of this control. The DTC controlled the supply and the price of diamonds.

Over time, more large scale mining companies entered the diamond business. The market share of DeBeers began to decline. However, due to rising demand worldwide, DeBeers’ sales did not suffer. The sightholder method of distribution remained but was restructured. Many of these invited companies were no longer in this group which is now called Supplier of Choice instead of sightholder. DeBeers wanted this restructuring for many reasons including better marketing efforts by all diamond companies and shared responsibility. They also wanted to eliminate their monopoly status that had kept them from certain business practices in the United States. The market share of DeBeers is now below 50%.

Rarity and Value

Even though new diamond exploration, including in Canada, has greatly added to the supply, the diamonds produced are continually bought up. Periodically, the industry will experience shortages of certain sizes, shapes, or qualities.

As a diamond gets larger it is more rare and therefore more valuable. Two diamonds of say one half carat each of a particular color and clarity will cost considerably less than one diamond of one carat even though they both have the same total weight.

The diamond grading scale described below is also a factor in rarity and value. Diamonds of very high color and clarity are much more rare than diamonds of lower color and clarity. Therefore, the price can be astoundingly different for two diamonds that are the same size but have differences in quality grades.

The 4 C’s

Most people today have heard of the famous 4 C’s made popular by DeBeers for consumers and the trade to judge quality, and hence, value when buying or selling. They are Color, Clarity, Cut, and Carat weight. The system was developed in the early 1950s by the Gemological Institute of America. It became a worldwide standard for grading and valuing diamonds. Some independent laboratories created their own grading systems such as the American Gem Society, ironically a sister organization to the GIA founded by the same person. Although the AGS scale differs from the GIA scale, the terms can be related back to the 4C’s of GIA.

Color

Color is graded on a scale that starts at D as the highest color grade. Many have asked over the years why the scale did not start at a higher color grade such as A, B, or C. The thought process behind this was to avoid confusion with other random grading systems that companies back then might have used to grade gems. D was an arbitrary grade with which to start the system.

D, E, and F are all considered colorless grades. They are the highest of white and only slight differences may appear with difficulty separating the grades under normal viewing. G, H, I, and J are all considered near colorless. These grades will normally still face up white to the untrained eye. K, L, and M, are considered faint yellow, though the tint may be also be brown. N through R are considered very light yellow (or brown). S through Z are light yellow (or light brown). Some lower color yellow diamonds may be referred to as “cape” or “canary.” Some brown diamonds may be referred to as “champagne” color. However, these fancy names for the lower colors of brown and yellow diamonds are marketing terms and are not used by major labs. As the diamond gets lower in color grade, it becomes less rare and hence less valuable. However, if the diamond has color below Z it is considered fancy color and then the prices will start to go back up. While a diamond may be many fancy colors, yellow is the most common. When the color becomes intense or vivid, the price of some yellow diamonds may be higher than the price of a D color diamond. Usually, the other colors of diamonds are rare and can be very expensive. Mostly, these colors are sought after by collectors. Red is the rarest of all colors and there are only a few truly red diamonds that have ever been mined. One million dollars per carat is not unheard of for a rare red diamond.

Clarity

The clarity grade of a diamond is determined by using magnification. The standard is ten power magnification, first by use of a microscope and then also by viewing with an instrument called a jeweler’s loupe. These hand held instruments are not easy to use without a lesson and they do take practice. So as a consumer, do not expect to purchase one of these and see the inclusions. They are handy however to view laser inscriptions that might be present on the diamond for identification. Diamond grading is a subjective process. However, trained professionals should be very close in their observations and conclusions. The higher the clarity grade, the more rare it is and of course the more expensive it is.

The highest clarity grade is FL or IF. These stand for Flawless and Internally Flawless. These diamonds have absolutely no imperfections seen under magnification.

The next two grades grouped together are VVS1 and VVS2. These diamonds are defined as Very Very Slightly Included. The imperfections in these are so tiny that even a trained grader might have difficulty locating the inclusions. They are usually a minor pinpoint or a few pinpoints as seen under magnification.

Next comes the VS1 and VS2 clarity grades. These diamonds are defined as Very Slightly Included. Small pinpoints and feathers might be found in these grades but they are still small relative to the size of the diamond.

Perhaps the most common clarity grades found are SI1 and SI2. That is because nature almost always puts inclusions in diamonds, so we accept them. In the SI category, these grades will usually have inclusions that are easy to see under magnification but rarely visible to the naked eye. SI3 is sometimes encountered on some laboratory grading reports or from jewelers when selling diamonds. It is important to note that this grade does not exist in the GIA grading system and is not endorsed by most major grading labs. While it may be represented as “low SI2” or a “bridge between SI2 and I1” or some other terminology, it is clearly a selling term. These diamonds are all I1 clarity at best and while some may attempt to allow only the “high-end” of I1 to get this grade, other diamonds may be anywhere in the I1 range.

The final clarity grade range includes I1, I2, and I3. The first of these diamonds (I1) has inclusions that may be larger in nature, may be dark, and may be eye visible among other possible attributes. Some I1 diamonds can still be very attractive depending on their individual attributes. I2 is a category where inclusions start to be very noticeable, detracting from overall beauty and potentially even affecting durability. The I3 category is reserved for diamonds that lack beauty and durability. Inclusions are so prominent in these diamonds that many of these will have little or no brilliance because light cannot pass through the diamond and reflect properly.

Cut

The cut of the diamond is often confused with the shape which is actually a completely separate value factor. Cut is all about proportions. The diamond diagram shown here has the parts of a diamond labeled. When evaluating a diamond for cut, each one of the facets is observed and measured for proper angles, length, and symmetry. A discussion of cut can become very technical. Those that want to study more information about the proportions and angles can do research through available books and online information.

Here is some basic cut grade information that applies to diamonds to help understand why proportions are important to the overall look and value of the diamond. Refer to the diagram for identifying features discussed in the following paragraphs. Understand that this information is the technical side of diamonds. What is important is how the diamond looks to you. Just because a proportion might not be ideally cut, the diamond may still look good to you and may be priced lower because of this. All information that follows pertains to round diamonds. Fancy shapes have completely different parameters to judge the diamonds.

Table. The table is the flat surface on the top of the diamond. The table is measured in millimeters and then divided by the average diameter of the diamond to get a table percent. 60% is the standard by which we compare as this is a very good table size. As the table gets larger, the light will not be reflected as well. Diamonds with tables above 65% are considered to be very large. Table sizes below 60% are considered to be more in the “ideal” range, down to about 53%. Below that, the table may be considered too small.

Depth. The depth of the diamond can be calculated by dividing the total depth from the top to the bottom of the diamond by the average diameter. Again, 60% is the standard for judging. If the diamond is too deep, it may appear dark. If the diamond is too shallow, it may loose brilliance as light leaks out. Normally, for a round diamond 57.5% to 63% is the “ideal” range.

Girdle. This is the edge that runs around the entire diamond where the top and bottom of the diamond meet. If the edge of the diamond is too thin, it might damage easily and get small chips and abrasions. If the girdle is too thick, it may alter the overall beauty and it also adds unnecessary weight. The possible grades are Extremely thin, Very thin, Thin, Medium, Slightly thick, Thick, Very thick, and Extremely thick. The normal range of acceptance for a girdle is thin to thick.

Culet. The culet is the point at the bottom of the diamond. The diamond should either have no culet (sometimes described as pointed), or be very small or small and possibly medium in size. A large or very large culet adds unnecessary weight and also affects the cutting angles of the pavilion (bottom) of the diamond.

Polish and Symmetry. These two features are considered the finish of the diamond. They reflect the skill and care taken by the cutter of the diamond. While they are microscopic in nature and rarely visible to the eye, they can affect the overall brilliance and beauty of the diamond. The grades for these are Excellent, Very good, Good, Fair, and Poor. Most diamonds today are cut with good or better finish features.

Prior to 2006, cut grades were not used by the GIA grading laboratory. Some other labs did use cut grades based on their own research and standards. For example, the AGS laboratory used a cut grade system that started at 0 as the “ideal” cut and went down from there (1, 2, 3…10). In 2006, the GIA introduced new cut grade standards but only for a standard round brilliant diamond. The cut grades are Excellent, Very Good, Good, Fair, and Poor.

Carat Weight

The carat weight of the diamond is determined by weighing the diamond on an accurate electronic balance scale. One carat equals .2 gram, so one gram would equal five carats. In the trade, these scales can be very expensive to obtain the accuracy down to the thousandth of a carat. The final representation is usually to two decimal places, though some labs will show the third decimal place. So, a one-half carat diamond would be represented as .50 carat, a one-carat diamond would be represented as 1.00, etc. An accurate weight is very important because the pricing is based on this weight, and there are significant differences in price sometimes over just one one-hundredth of a carat. A diamond that weighs .99 carat is lower priced than a diamond that weighs 1.00 carat.
 
In the international gem trade, the standards for weight representation are different than some local laws and standards. This can make things confusing. In the international trade, you can only round up to the nearest one-hundredth of a carat if the thousandths place is 9. If it is 8 or below, it must be truncated. So, a diamond that weighs .998 carat is bought and sold in the trade as .99 carat. If it is .999, then the diamond can be rounded to 1.00 carat. The confusion occurs if a store wants to sell the diamond based on local laws that might disagree with this method. In the U.S., the Federal Trade Commission Guidelines state that normal mathematical rounding applies, so a diamond that weighs .995 can legally be sold as a 1.00 carat diamond. But since most one carat diamonds have grading reports from a recognized trade laboratory and most jewelers follow the trade rules, this diamond would be sold as .99 carat.

Diamonds are more expensive per carat as each new carat weight category is reached. This chart shows the general guidelines for where these price increases occur.

• Note that there might be slight premiums in some of the above categories as diamonds get closer to the next category.

Fluorescence

Fluorescence is a greatly misunderstood concept. Fluorescence is the reaction of trace minerals within the diamond that cause the diamond to glow when exposed to ultraviolet light. In the laboratory, special ultraviolet lamps are used to check for this but the sun is also a source of ultraviolet rays so diamonds will react in daylight as well. About one third of all diamonds fluoresce. Of these, the most common color is blue, but diamonds can fluoresce other colors. More than 95% of those that do fluoresce will fluoresce blue. The next most common color is yellow. Any other color of fluorescence would be rare.

There are some educational sites or selling sites that discuss fluorescence as a negative value factor. When a diamond fluoresces blue it has a tendency to appear higher in color than its true body color. This is a good thing. However, many years ago, fluorescence was thought to be a negative, and the reasons can only be speculative. One such reason was that it was thought that perhaps the color grade assigned was lower than its apparent color, so people were fearful that they would be paying too much for a diamond. For example, a J color diamond might look like an H or an I color if it had fluorescence. But as long as the diamond is correctly graded as J, then the fluorescence is really like a bonus. The diamond looks higher in color than the price suggests.

Two factors should be considered regarding fluorescence. The first is the color of the fluorescence. If the diamond fluoresces blue, it may be a positive factor since it will make the diamond look whiter. However, note that there is still a stigma against fluorescence and some people will simply not buy the diamond and some sellers will offer a discount for fluorescent diamonds in the higher colors. If the diamond fluoresces yellow, this is a negative factor because the diamond will look lower in color in ultraviolet light.

The second factor is the strength of fluorescence. The range of strengths as reported on laboratory grading reports is None, Faint, Medium, Strong, Very strong. Some labs use the term Negligible for any diamond with no fluorescence or faint fluorescence. Sometimes when a diamond has very strong fluorescence, the diamond will have an “oily” look to it, even in normal lighting conditions. When this happens, a negative value is expected. The range of discounts that might be realized are anywhere from 0% to 15%, but a large discount is rare. Occasionally, a slight premium of 1% to 3% might be added for a diamond that is in the lower color grades but exhibits fluorescence.

Light Performance

Until the early 2000s, very little information was revealed on light performance. Light performance is a direct result of the cutting proportions of a diamond. The standard terms that are used for light performance are the brilliance, fire, and scintillation.

Brilliance is the amount of “white” light reflected by the diamond. The eye often perceives white light as brightness, a positive attribute of diamonds.*

Fire is the amount of spectral “color” or rainbow effect reflected by the diamond. Sometimes referred to as dispersion, to the eye this phenomenon gives diamonds a unique fiery appearance.*

Scintillation is alternating beams of light or sparkle reflected by the diamond as it or the light source moves. To the eye, this sparkly effect gives diamonds their glamorous appeal.*

Light performance information is not always available on the diamond you may be considering buying. Some labs offer this information and some diamonds have auxiliary light performance reports. Grading light performance is not based on one set of standards, so the information may not be fully reliable. Each system has its own set of standards. One thing is certain. If a diamond is cut well, you will see the light performance because the diamond seems to “talk back to you.”

*Definitions of brilliance, fire, and scintillation are from Gemworld International Laboratories diamond grading reports.

Laser Inscriptions vs. Plotting

Back in the 1950s when the diamond grading system was developed, plotting was also developed. This was a system of drawing the inclusions and surface characteristics of a diamond on a line diagram of the diamond. The original purpose of a plot was to identify the diamond if necessary at a later date. Plotting can be time consuming, especially when a diamond has many inclusions. Plotting also has a tendency to make a diamond look worse than it actually is because tiny microscopic features are now plotted larger than life on a diagram of the diamond.

Then, in the 1980s, laser technology advanced and laser inscriptions started to be etched on the girdle edge of the diamond. These inscriptions often were of the grading report number but could also include logos and even personal messages. As these became more popular, some labs such as the GIA began offering a laser inscription in lieu of a plot for identification. No standards exist for when a plot should be performed or when a laser inscription will suffice for identifying the diamond. This is a personal choice of the labs and their policies, the appraisers and their policies, and the consumers and their preferences.

Diamond Treatments and Synthetics

Detecting diamond treatments and synthetic diamonds are a challenge to the entire industry. Some diamonds treatments are more challenging than others to identify. Here are the main diamond treatments and synthetics to know about.

Synthetics

Synthetic diamonds are identical to natural diamonds in their chemical characteristics. Methods to identify these exist and while they can be challenging and sometimes require expensive equipment, they are not thought to be a significant threat.

Note that there are several diamond imitations, most notably cubic zirconia and synthetic moissanite. Neither of these poses great challenges in identification for an experienced grader.

Laser Drilling

When diamonds have black inclusions, they may not be very appealing to the eye. A process for removing these black inclusions developed in the 1960s and had widespread use by the 1970s. First, the laser is focused on an inclusion and a microscopic drill hole is left behind. This allows an acid bath to enter the diamond and remove the black imperfections. Although  this is done in an effort to improve the appearance of the diamond, one can debate whether it really does since it leaves a drill hole and white inclusion where there used to be a black inclusion.

Most laser drilling is easy to identify. However, some newer methods are more challenging since they do not leave a drill hole. Pricing is erratic. Some will lower the price of the diamond due to the drilling process, while others will not, arguing that the diamond may still have the same clarity grade but with slightly improved appearance. The important thing here is disclosure. In the U.S., it is required to disclose all diamond treatments. As long as consumers know what has been done, it is then up to them to make an informed buying decision.

HTHP

HTHP is the abbreviation for “High Temperature, High Pressure.” This treatment was perfected in the early 2000s for changing the color of a diamond using nothing more than controlled heating combined with high pressure. These expensive presses are effective on some diamonds and can change the color from a low yellowish or brownish color all the way up to D, E, or F colorless. The same process can also be used to change some diamonds into fancy color diamonds such as intense yellow or other colors.

Detecting this treatment is the most challenging in the industry. Sometimes, microscopic signs are left behind that can be proof positive of the treatment. But other times, there are no signs. Sophisticated equipment can act as screeners for these treatments.

Irradiation

Irradiation of a diamond is used strictly to create fancy color diamonds from off-color inexpensive diamonds. The process is controlled and stable. Resulting colors can be a wide range including green, yellow, orange, pink, and even red. Some irradiated diamonds are relatively easy to detect with simple tests and magnification while some require more extensive testing and equipment.

Clarity Enhanced

This process involves the use of a lead-based glass that through heating and pressure, is imparted into the diamond, effectively hiding the feathery type of inclusions. The film-like layer of glass is so fine and minute that it does not add significant weight (if any at all) to the diamond. The process is very effective in masking these inclusions.

The correct term for this treatment is clarity enhanced, though many in the trade prefer to use the term fracture filled. Diamonds do not have fractures that are being filled; they are cleavages (feathers), and gemologically speaking, there is a difference. As long as the treatment is properly disclosed, it again is up to educated consumers to decide if this product is for them.

It also is important to note that the treatment may not be stable. Care should be taken with these diamonds. They should not be placed in an ultrasonic cleaner. If repairs are to be done by a jeweler, the jeweler should be informed about the treatment as the high heat generated by a jeweler’s torch would damage the filler. It can be retreated if this should happen.

Buying a Diamond

This should be a wonderful experience but unfortunately for many it is a time of apprehension, mistrust, and nervousness. Realize that jewelry is a personal item and everyone has different tastes. After finding an item you like, get it certified and appraised.  The guarantee is important. That is what gives you the confidence and takes away the nervousness.

Laboratory Reports

Today, most major diamonds are sold with a report from one of dozens of “independent” laboratories. These laboratories offer opinions of the quality grades of the diamond and possibly other information such as cut grading and light performance. It is important to note that not all laboratories are created equal. Some labs are known in the trade to be more “lenient” in their grading of the diamonds where others may be more strict. Consumers often wonder how this can be since diamond grading is considered a worldwide standard.  Although it is true that a standard exists, the system is still subjective. Some labs rely on this subjectivity as a fallback position to allow them to be more lenient.

Other factors that affect the quality of the lab are the number of graders that are required to look at each diamond (some labs may require only one while others may require as many as three), the experience of the lab, the quality control procedures, etc. Therefore, when comparing diamonds and diamond prices, the 4Cs are not the only factors to consider for a valid comparison. The laboratory should also be considered. We are not saying to accept one over another but to be aware of the differences that may exist.

Colored Gemstones Quick Reference Guide

To be classified as a gemstone, an organic or inorganic material must possess beauty, rarity, and durability. A gem’s beauty comes from its brilliance, fire, luster and color. Often gemstones are enhanced by a variety of methods such as heat or oil to improve their appearance. Many of these treatment methods have been done for more than 100 years, so they are not new. However, all gem treatments should be disclosed to the consumer.

The light that the gem is viewed in can have a dramatic effect on its perceived color. Even natural daylight will vary in different parts of the country or the world. Gems purchased overseas may look very different when brought home.

Two common gemological properties of a gemstone are its density, referred to as specific gravity, and its refractive index. Colored gems have varied densities. That is why a one carat ruby will look smaller than a one carat diamond or emerald if cut in the same proportions. The density of ruby is greater than either of the other two gems. The refractive index refers to how many times faster light travels through air than through an object. Gems with higher refractive indexes may be more brilliant in appearance if cut properly.

The value of a colored gemstone is based on the value factors of color, clarity, and cut. The color is the most important factor, often counting for 50-75% of the gem’s value. Color is described as its hue (primary color), its tone (how light or dark the color is), and its saturation (how vivid or how gray or brown the color is).

The clarity assessment for colored gems varies with each variety. That is because the gems grow differently in nature. An easy type classification system is used in the trade. TYPE I gemstones grow very clean in nature such as aquamarine. Inclusions would be more detrimental if easily seen. TYPE II gems grow with moderate inclusions and most gems get this type classification. Ruby and sapphire are in this type classification. TYPE III gems grow with many inclusions. Emeralds are in this class and we grade clarity more lenient since nearly all emeralds have some eye visible imperfections.

Cut refers to the skill in the overall finishing of the diamond. These are the proportions, the polish, and the finish of the gem. Well-cut gems will be very brilliant. Shallow cut gems will exhibit “windowing” where one can read text right through the gem. Deep cut gems will have “extinction,” or dark areas of the gem with no brilliance.

Treatment refers to any process other than other than cutting and polishing that improves the appearance of the color or clarity, or that are used to alter the appearance (color, clarity or phenomena), durability, value, or supply of a gemstone. Today, most gems are treated to improve appearance. Treatment processes can consist of heat, irradiation, dyeing, oiling, or other processes. Detection of these treatments may be easy to nearly impossible. Treatments should always be disclosed to the consumer.

Colored Gemstones

Information on this education section has been prepared by Gemworld International, Inc., an authority in the jewelry industry providing unbiased information since 1982.

Introduction

The term gemstone is applied to any of the one hundred or so naturally occurring minerals (diamond, ruby, sapphire, etc.) and organic materials (amber, pearls, ivory, coral, etc.) that are used for personal adornment or display. However, most of the popular gem materials encountered today are inorganic. The first use of a mineral or organic substance for personal adornment remains the subject of debate. But it is generally accepted that their use dates back at least ten thousand years.

To be classified as a gemstone, an organic or inorganic material must possess beauty, rarity, and durability. A gem’s beauty comes from its brilliance, fire, luster and color. In their rough form these attributes are often masked. Only after cutting and faceting and often other enhancements, can the true beauty be revealed. Durability refers to a combination of the material’s hardness (ability to withstand scratching), toughness (ability to resist breakage), and stability (ability to withstand chemical or physical change resulting from heat, light or chemical exposure). There are approximately 2,700 different minerals on record. However, less than one hundred are regarded as a gemstone or ornamental variety for jewelry use and fewer than 50 are regarded as common. 

Gems are grouped by their composition and classed by species and variety. Minerals form at different depths within the Earth. Some form close to the surface when solutions containing minerals and water experience a change (usually the evaporation of water) triggering the crystallization process. To illustrate this process one can dissolve salt into warm water. Let the water stand for a few weeks at room temperature and as it evaporates the salt crystals will form as the amount of water diminishes to a level where the salt can no longer be held in solution.

Most gem varieties formed at depth from the elements present in the Earth’s mantle. Initially these elements may be contained in molten mixtures called magma. As the molten material was forced closer to the Earth’s surface by various processes, the mixtures cooled and minerals crystallized. Because silicon, oxygen and quartz are abundant in the Earth, it is no surprise that most gems are silicates, oxides and quartzes.

Colored Stone Mining and Distribution

Chances are that if I say “A diamond is forever,” you will think of DeBeers. At one time or another we have all seen one of its commercials promoting diamonds. But have you ever seen a similar commercial promoting a colored stone? Probably not, there is a significant difference between the way diamonds and most other gemstones are mined and distributed.

Unlike colored stones, activity in the diamond market is controlled by few major mining companies, the most influential of which is DeBeers. DeBeers directly or through one of its related entities such as the Diamond Trading Company, monitors the release of product into the distribution channels as a controlled response to demand. The supply is known; the demand is known; and the price is known, long before the diamonds reach the market.  

By comparison, colored stone prices are predominantly influenced by free market conditions. Colored stone deposits are usually worked by small scale independent miners. Production costs are relatively inexpensive compared to the tens or even hundreds of millions of dollars that can be invested into a diamond mine during its production life. Colored stone miners often sell their rough in markets that are visited by international cutters. The price will be negotiated based on supply and demand. 

Recently, producing nations have become increasingly aware of the value of their mineral wealth and are exerting more influence over its production. More governments are joining in partnership with the private sector in exploration and mining. The aim is for a greater percentage of the mineral wealth to benefit the host nations. Traditionally, gem rough was either seriously undervalued or smuggled out of countries by dealers aiming to avoid export fees and taxes. As a result, virtually no benefit was derived by the populations living in the host countries.

Gem rough can be mined from both primary and secondary deposits. A primary deposit is one in which the gem crystals are still contained in the host rock. Mining of this type involves pits or tunnels that follow the gem-bearing vein. The gem rough is extradited from the host rock using tools, chemicals, or explosives.

Most colored stone rough is mined from secondary deposits. That is to say the deposit of rough is located in an area other than where the gem rough was formed and transported toward the surface. Secondary deposits are areas where the rough has been transported to and deposited after being freed from its host rock by natural processes including weathering or erosion. Often these deposits can be active or dried riverbeds.

Unlike the open pit and underground mining associated with the Earth’s largest diamond mines, colored stone deposits are often mined with little more than a shovel, bucket and rope and a kerosene generator to pump air into the tunnel. If the deposit is associated with an active river or stream, mining may consist of shoveling gravel into a pan or sieve where any gem crystals present are extracted by hand. This is an extremely time consuming and laborious process.

Once mined, rough gems eventually end up in one of the world’s main cutting centers, for colored stones, usually Thailand or China. However, more nations that host gem deposits are investing in the development of cutting centers as a means of adding value to and increasing the benefit derived from their mineral resources. Madagascar is a good example of one such nation. Although mineralogically rich, this island nation located off the east coast of Africa had the distinction of being the third poorest country on Earth. However, in 2003 with financing from the World Bank, Madagascar launched an initiative to retain the wealth that its resources represented and stem the illegal smuggling of rough out of the nation. The consultant working for the government developed and launched gemology and stone faceting programs designed to assist the Malagasy people gain careers in the international gem trade. Now, many of the gems mined in Madagascar are also cut and polished in Madagascar. These programs have been highly successful and serve as models for other regions on the continent. 

Lighting and Color

Above we mention the role that faceting plays in revealing the beauty of a gem. However, the single most significant factor may well be the role that light plays in exhibiting the color of a gemstone. In fact, gems are cut and faceted in the shape and styles that the cutter believes will achieve the best results from the stone’s interaction with light in showcasing its attributes. Many factors influence the cutter’s decision, including the type of gem, shape and size of rough, etc. The type of lighting used to illuminate a gem can affect the color and quality of color we see. Some consider natural daylight as a standard. However, daylight can vary depending on geographic location and time of day. A stone viewed in natural daylight in one location may look different when viewed in daylight in a different geographic location.  

White light is critical in unlocking the colors we see. Light is a form of energy. White light is actually composed of individual colors ranging from violet through blue, green, yellow orange and red. When these different wavelengths are present in equal amounts, our eyes perceive it as being “white.” But if an object absorbs certain wavelengths more than others (“selective absorption”), the result is color.

If one passes white light through a colored object, like a gemstone, any portions of the spectrum that are missing represent areas of absorption. It is these areas of absorption that result in visible color perceived by the eye.

The primary causes of the color we see in gems can typically be attributed to impurities, charge transfer, or color centers. There are also other causes but for the purpose of this cursory explanation of the topic only these three common causes are discussed. 

Impurity

Impurities (trace elements not found in the pure mineral form) contained in a gemstone are responsible for the color we see. For example corundum is the species of mineral to which ruby and sapphire belong. In its pure form, corundum is colorless. However, when chromium impurities are trapped in the corundum during crystal formation the crystal exhibits a red color. The strength of color is dependent on the amount of the impurity(s) present. The same impurity will have different effects on different minerals. Chromium creates red in corundum (ruby) but green in beryl (emerald).

Charge Transfer

For a charge transfer to occur, a compound must have at least two elements in different and variable oxidation states. If this condition is present, it is possible for electrons to be swapped between two elements as energy from visible light is absorbed and transfers electrons from one atom to another. This can result in color formation of alternation.

Color Centers

Color centers are imperfections in the crystal lattice that cause color by absorption of light. The defects are usually the result of radiation damage.
  
Many gemstones will exhibit different appearances when viewed in fluorescent and incandescent light. The energy wavelengths associated with these light sources differ from one another. In certain gems by changing the light source, one can actually change the color of the gem. Alexandrite is an example of a gem that changes color from incandescent to fluorescent light.

Many jewelry stores have bright halogen lights over the jewelry showcases. The intensity of these lights brings out the beauty of the gemstone. But if you would like to know what a gemstone is really going to look like in normal viewing conditions observe it away from the case where lighting is more subdued.

Gemological Properties of Gemstones

Gemstones have certain properties that gemologists rely on to aid in identification. These include density and refractive index and visual characteristics among others.

Density

Density refers to the physical property of matter that describes how tightly pact together the atoms of an element or molecule of a compound are. The more tightly packed the individual particles of a substance are, the denser the substance is. Understanding density is a useful tool in identifying minerals since substances have different densities. For example, a ruby and an emerald of the same size and cutting style will have vastly different weights. This is because the density of the ruby is greater than that of the emerald. Therefore, a one carat ruby will be smaller in size than a one carat emerald.

In gemology we measure density via the specific gravity (SG) of a gem. Specific gravity is defined as the ratio of the weight of a substance to the weight of an equal volume of water. The SG of a gem can be measured using a scale and water. Specific gravity varies with chemical composition and crystal structure type. Therefore it can be very useful in identifying minerals.

More commonly, however, the SG of gems is approximated by comparison using heavy liquids. Gemologists use sets of liquids of known SG values to perform the comparison. The stone (faceted or rough) of unknown identity is immersed in the heavy liquid of know SG. The stone is observed to see if it floats (lighter than), sinks (heavier than) or is suspended in (equal to the weight of the liquid). Depending on the result, the stone may be cleaned and then immersed into a different liquid within the set. This process is repeated until the SG of the stone is obtained or all other potential gem varieties have been excluded by process of elimination. Once the SG is obtained the gemologist will refer to a gemological properties chart of SG values to match it with the corresponding gemstone.

Refractive Index

Another important property used to identify gems is the refractive index (RI). After visual observation, the RI is often the first test a gemologist will perform to identify an unknown gemstone.

Refraction occurs when light enters a transparent or translucent material or liquid from air causing its speed and direction to change. We have all observed this phenomenon in life. For example, the underwater portion of a canoe paddle appears at an angle to the handle portion above the waterline. As light enters a gemstone its speed is reduced. This sudden reduction of speed causes the light to bend. Therefore, refractive index refers to how many times faster light travels through air than through an object. The refractive index of diamond is 2.42. Essentially this means that light travels through air at a rate of 2.42 times faster than it travels through diamond. The slower light moves through a gem the higher the RI will be.

The instrument used to measure RI is called a refractometer. Once the RI of the subject stone has been determined the gemologist will refer to a chart of known RI properties to identify the stone. Because gems of the same variety can have slightly different chemical compositions or structures, there can be slight differences of RI value, so RI is often expressed as a range on gemological data charts. For example, the RI of emerald can range from 1.577 to 1.583. However, each gem type has a distinct RI. Although there can be overlap between related materials, visual observations are sufficient to make the proper identification. For example, the RI of garnet and ruby can overlap. However, the single refractive nature of garnet (light travels at the same speed regardless of direction) is sufficient to separate it from doubly refractive gems (light splits into two beams each traveling at a different rate of speed) such as ruby.

Gemologists use a myriad of other characteristics and properties to identify gem materials. These can include the hardness of the stone, observation of diagnostic inclusions, growth zones and color. The gemologist’s best asset is experience.

Value Factors

Just because a stone is a sapphire or emerald or other gem variety does not automatically mean it has value. Most gem deposits typically produce much more low quality rough than they do rough with gem potential. Minerals such as diamond, corundum and quartz have industrial applications, so even in low quality form they are desirable to mine. But others do not. What are the factors that determine if a piece of gem rough has value?

Color

The measures used to evaluate the quality of a gemstone have been developed over centuries. Ancient writings from China, Egypt, India and the Roman Empire have described the value factors associated with gems over thousands of years. The valuation of gems observed in the industry today has been an evolving process. One common thread in this process has been the importance of color. As is implied in the term colored stone, the single most important factor to a gemstone is color. Some colored stone experts estimate that the color component of a gemstone can account for 50% to 70% of its value.

Gemologists consider a gem’s body color in terms of hue, tone and saturation. Combinations of these properties help create the colors we observe. I say “help create” because color is not an absolute: it is a perception of the interaction between the object, eye and brain of the observer. In other words, color occurs when seen, and the typical human can see about 10 million different colors! (GIA Colored Stones Course)

Hue is the base color that first stands out when viewing a gemstone. For example, blue, violet, purple, red, orange, green and yellow are all hues. Combinations of these can form additional hues. For example a common color in tanzanite is purplish blue. The Gemological Institute of America identifies 31 base hues that can be used to describe most gems. That chart consists of the 7 base hues listed above plus 24 combinations of the above.

Tone describes the degree of lightness or darkness of a color. For example, a red stone can be dark red, medium red or light red. The color may also be between two tone values, i.e., medium light red. The GIA tone scale has 11 positions ranging from colorless to black. Black and white are not considered hues. They are the extremes of the tonal scale.

Saturation refers to the degree of intensity of a color. The GIA saturation scale groups hues into cool hues, (including blue and violet) and warm hues (including orange and red). Cool hues can look grayish as their saturation of color decreases, while warm hues can look brown as their saturation level decreases. The GIA saturation scale identifies six degrees of saturation. These range from grayish (in the cool hues) or brownish (in the warm hues) to vivid. Desirable saturation levels for most gems fall in the moderately strong, strong or vivid range.

The relationship between hue, tone and saturation is important in valuing a colored stone. The body color that we observe in the gem is a combination of these properties. Usually as a gem becomes more saturated, it will also have a darker tone. While the most valuable gem will be a 6-vivid on the saturation scale, the most valuable gems will not be the highest tone value of 8. These gems are actually too dark in tone. The optimal tone is typically medium to medium dark, 5 to 6 on the tone scale. Different gems have different optimal tone values based on what nature provides us.  An example of this is aquamarine, which almost always has a lighter tone of blue vs. sapphire, which often has a dark tone of blue. Both may be the same hue, but the optimal tone expected to see in the market is much different for both.

When examining a gemstone, be aware of the light source used to illuminate the gem. Ask yourself, will the stone have the same appearance in normal viewing conditions?

Clarity

Clarity refers to the relative degree to which a transparent gemstone is free of internal or surface characteristics or imperfections. Internal characteristics are commonly referred to as inclusions and external characteristics are commonly referred to as blemishes in the gem trade. The types of inclusions encountered in gems include needles (mineral fibers that formed during crystallization), crystals (small mineral crystals of the same or different type as the gem that formed in the host), pinpoints (tiny crystals), feathers (natural separation across an atomic plane), fingerprints (a healed or partially healed break in the gem), color zoning, chips, scratches, etc.

Inclusions are not necessarily a negative feature to a gem. Certain gems cannot exist without them. Cat’s eye chrysoberyl and star sapphire require needle inclusions to create the desired phenomena.

Gemologists consider the type, size, number and position of inclusions when considering clarity. They also consider how noticeable the inclusions are. Gemologists study the type of inclusion because certain inclusions pose a greater likelihood that the gem could be damaged under normal wear than others. They study the size because usually the larger the inclusion the more it may detract from the stone’s appearance or pose a concern for damage. The number of inclusions is considered in relationship to the size of the inclusions. Numerous small inclusions typically will not impact the value of a gemstone to the extent that one large inclusion can. The position of an inclusion refers to its location within the stone. For example, an inclusion positioned under the table facet is likely to be more apparent than one located near the girdle. 

Minerals form in different environments and from different chemical elements. As a result, some varieties are more prone to containing inclusions than others. The GIA clarity grading standard for colored stones takes this fact of mineralogy into consideration. Colored gemstones are typed as Type I, Type II or Type III. Type I gems grow extremely clean in nature and usually have no eye visible inclusions. Type II gems typically grow with some minor eye visible inclusions. Type III gems almost always form with many eye visible inclusions. Most popular gemstone varieties fall into either type I or type II. With consideration of the type classification, the clarity is graded as Eye-clean, Slightly included, Moderately included, Heavily included, or Severely included.

It was stated earlier that color is the most important factor in evaluating a colored stone. It should be noted that if a type I gem (such as aquamarine) has numerous, large eye visible inclusions this will have a significant negative impact on value regardless of how strong and pure the color is.

Cut

Here, cut refers not to shape of the stone round, pear etc, but to how well the proportions, symmetry and polish are executed. How well a gem is cut can greatly affect the overall value because of its influence on color. Well cut stones bring out the beauty and brilliance more, thus increasing the overall grade. Poorly cut stones will see light leak out of the stone instead of being returned to the viewer’s eye.

There are many factors to consider when valuing the cut of a gemstone. Brilliance, windowing, extinction, polish and symmetry are all factors that should not be overlooked.

Brilliance refers to how bright or glittery a gem is. Windowing refers to the washed out area of body color in a gem. If there is a significant degree of windowing in a gem, one can usually read text placed underneath the stone when the stone is placed in contact with the text. Windowing is common in stones that are cut too shallow. Extinction refers to dark areas in the stone. Extinction is encountered in stones that are cut too deep or have significant pavilion bulge (rounding of the pavilion). Polish and Symmetry refer to how sharply and well defined the relationship is between the crown (portion above the girdle) and the pavilion (portion of the stone below the girdle). When care is taken, all facets will be polished well and the arrangement will align the facets properly for the shape of the gemstone.

When combined, the evaluation of color, clarity and cut result in a total grade that considers these three factors. While no grading standard exists, a trade publication produced by Gemworld International, Inc. uses terminology of Commercial, Good, Fine and Extra fine to refine this step.

Gemstone Treatments

Treatment refers to any process other than cutting and polishing that improves the appearance of the color or clarity, or that are used to alter the appearance (color, clarity or phenomena), durability, value, or supply of a gemstone.

Today, most gems are treated to improve appearance. Treatment processes can consist of heat, irradiation, dyeing, oiling, or other processes. Detection of these treatments may be easy to nearly impossible. Treatments should always be disclosed to the consumer.  The following is adapted from the American Gem Trade Association Treatment Disclosure Codes.

Dyeing refers to one of the oldest treatments recorded. The treatment involves the introduction of a coloring agent into a gemstone to give it a new color, intensify an existing color or improve color uniformity.

This is a brief list of treatments commonly encountered in the gem trade. It is not all inclusive. Other treatments exist.

Gemstone Buying Guide

Buying a gemstone can be a daunting task. It is an experience that requires trust, not only of our senses in judging what we can discern about the gem one is considering, but also the representations of the person selling the gem.  Many factors set value. Some of them like weight are tangible; others like clarity, color or origin are not. Gemstones may be accompanied by a lab report listing the color, cut, clarity and weight. They may also contain a comment about treatments or origin. Certain gemstones such as ruby or sapphire can receive a premium in the market if they are believed to be from a particular country (origin). In lieu of an independent grading report, the seller may offer certain guarantees.

Consumers must reconcile their budget with their tastes. A smaller gem of finer quality will cost as much or more than a larger gem of lesser quality. Nature produces far fewer of the top quality gems, so there is good reason for the greater price.

The following is a summary of factors for some of the most popular gems in the trade. 

Ruby

Ruby is generally considered the most valuable of the colored gemstones when priced per carat for exceptional quality gems. It is considered one of the “big three” in the industry—ruby, emerald, sapphire.

Color:

Rubies vary in color from orangy red, red slightly purplish red, strongly purplish red, to red.

Clarity:

Type II—May be eye clean with minor inclusions visible under magnification.

Cut:

Some native cuts may be found (gems cut at the mine location without high regard to skill in cutting). However, well-cut stones are available.

Carat weight:

Stones weighing more than 5 carats in finer qualities are very rare. In commercial grades, stones are available from in all sizes up to 10 carats.

Reference Data:

Refractive Index: 1.762-1.770, Specific Gravity: 4.00

Common Treatments:

Most rubies are heat treated to improve color. Some may also be heated in the presence of flux which can leave residue within the ruby, known as flux healing. Another method of filling fissures uses lead glass and leaves this residue inside the gemstone.

Emerald

Emerald is one of the most valuable gems, prized throughout history. It is considered one of the “big three” in the industry—ruby, emerald, sapphire.

Color:

Very strongly bluish green, bluish green, very slightly bluish green, green and slightly yellowish green.

Clarity:

Type III—usually has eye visible inclusions.

Cut:

Some native cuts may be found (gems cut at the mine location without high regard to skill in cutting). However, well-cut stones are available.

Carat weight:

Stones weighing more than 8 carats are rare in finer quality. In commercial qualities, stones are available in all sizes up to 20 carats or even larger may be encountered.

Reference Data:

Refractive Index: 1.577-1.583, Specific Gravity: 2.72

Common Treatments:

Nearly all emeralds are oiled with a variety of oils, some with resins added. Filling of emeralds may also take place. These treatments help to hide the natural fissures within emeralds which is a common feature of their growth in nature.

Sapphire

Sapphire is the most popular gemstone in the United States. It is considered one of the “big three” in the industry—ruby, emerald, sapphire.

Color:

Sapphires can be found in a variety of colors in each of the seven primary hues. However, blue is the most common, most desired, and most expensive.

Clarity:

Type II—May be eye clean with minor inclusions visible under magnification.

Cut:

Some native cuts may be found (gems cut at the mine location without high regard to skill in cutting). However, well-cut stones are available.

Carat weight:

Stones weighing more than 20 carats is rare in finer qualities. In lower grades very large sizes are available.

Reference Data:

Refractive Index: 1.762-1.770, Specific Gravity: 4.00

Treatment:

Heat is very commonly used to improve the color of sapphires.

Tanzanite

Tanzanite is a very popular variety of zoisite. It gained popularity in the 1970s when Tiffany & Co. brought it to market.

Color:

Purple, bluish purple, violet, bluish violet, violetish blue and blue. Tanzanite is highly trichroic meaning it exhibits different colors when viewed in different directions. How it is cut by the cutter will also affect what color results in the finished gem.

Clarity:

Type I—Usually eye clean with high clarity under magnification.

Cut:

Well cut stones are expected.

Carat weight:

Stones weighing up to 20 carats are available in finer qualities and up to 50 carats are available but rare.

Reference Data:

Refractive Index: 1.691-1.70, Specific Gravity: 3.35

Treatment:

All tanzanite are heated to obtain the color.

Commonly Recognized Birthstones

• January: Garnet
• February: Amethyst
• March: Aquamarine
• April: Diamond
• May: Emerald
• June: Alexandrite 
• July: Ruby
• August: Peridot
• September: Sapphire
• October: Opal
• November: Topaz
• December: Zircon (now tanzanite on some lists)