Diamond Certification

The quality of a diamond is based upon its cut, color, clarity, and carat. The higher a diamond is graded in cut, color, and clarity, the better its quality. And, a higher carat weight can be desirable as well. As the grades and weight of a diamond increase, so does its price. Thus, it is very important to know precisely the cut, color, and clarity grades that make your diamond what it is. The Gemological Institute of America (GIA) grades diamonds provides a certificate of the grading. This certification of a diamond is proof that your diamond is of the quality stated and is good consumer protection as well. It takes an expert gemologist to accurately distinguish one higher cut grade, color grade, or clarity grade from another. The GIA picks 4 or more gemologists at random to grade and certify a diamond.

When a diamond is certified it comes with documentation of the certification process. This document specifies what, if any, inclusions the diamond has, whether it is perfectly clear or has various minor degrees of yellowing and the quality of the cut of the diamond.

A non-certified diamond may come with various descriptions. But it is the GIA grading certificate that precisely defines each element of quality of your diamond.

What Are the Advantages of a Certified Diamond?

With uncertified diamonds, there is an issue that should concern everyone who buys one. Diamond prices are determined by the grades of the diamond’s cut, color, and clarity and by carat weight. But, the average diamond buyer is in no position to understand the precise grades.

Anyone can tell that a perfectly cut diamond sparkles more than a sloppy and off-center cut. And, we can all see that the most color-free white diamond is different from a low-grade and yellow tinted diamond. Absolutely clear diamonds clearly have more brilliance and fire than diamonds low on the clarity scale. And, a five carat diamond is certainly easy to differentiate from a 0.25 carat gem.

The issue is to determine the difference between any two adjacent grades of cut, color, or clarity and between diamond sizes of nearly equal carat. The GIA is trusted for its expertise in evaluating diamonds and for its judgment and integrity in carrying out the process.

An old trick from the days before certification was to tell the buyer that their diamond was a higher grade in cut, color, and/or clarity than it really was. Of course, the price of the diamond was based on the fictitious grading. And, because a woman commonly wore the ring for her entire life, no one was the wiser. But, if for any reason the woman wanted to get a new diamond, she would be severely disappointed when told that her diamond was not the quality or value that her husband had paid for!

The take-home points of the lesson:

  • A diamond grading certificate gives you proof of authenticity, ownership, and value. And, if a diamond is lost or stolen the certificate provides proof of value.

  • Diamond certification is the basis for an appraisal of value.

  • When you certify your diamond you are assured of its quality and value.

  • Certification should always be done for perfect and near-perfect diamonds. The amount of money involved between on high grade of cut, color, or clarity and the next one up can be very significant and not certifying such a gem is simply foolhardy.

The one disadvantage of certification and the really high-end diamonds that require certification is the high cost of the gem.

Advantages of Non-Certified Diamonds

Maybe you like a diamond, trust the jeweler, and the price is not that high. Here are advantages of buying less expensive and non-certified diamonds.

  • These diamonds cost less than the certified variety

  • You do not need to fuss with the GIA checking grades and your waiting for the results

  • You will have a wider selection of diamonds to choose from

  • What you will be readily available, no waiting

The disadvantages of buying a non-certified diamond are that you may be getting less quality than you think and paying more as well. It is totally possible to end up paying twice as much as necessary if an unscrupulous jeweler manipulates the grading numbers for your diamond.

Where to Get Your Diamond Certified

We have only mentioned the Gemological Institute of America but there are other organizations that will evaluate and grade your diamond. Here is a little information about certifying organizations, their reports and how each might or might not affect the diamond price. Each of these is recognized as experts in gem classification. And each has a slightly different system.

American Gem Society (AGS)

This organization dates back to the 1940s and has been non-profit for the last two decades. The AGS grades princess, emerald, oval, round, and cushion cuts without unusual or so-called fancy terms attached. They employ an unusual and one of a kind cut grade method. Their diamond grading reports are simpler, clearer, and easier to understand than other grading reports. The precise effect on the diamond price of getting AGS certification is unclear. However, certifying with AGS does have the definite effect of raising the price of a diamond above its non-certified value.

One of the unique AGS grading features is “performance” which is a composite of weight/size ratio, proportion, light leakage and dispersion, and finish.

Their certification also notes if a diamond has been altered such as by filling fractures.

European Gemological Laboratory (EGL)

The EGL has branches all over the world but their certifications primarily affect the prices of diamonds in Europe. These folks originated clarity grade SI3 and are known for rating methods for gems of slightly less than one carat weight. There is an ELG USA branch and an EGL Platinum lab in Israel.

Rating by EGL includes symmetry, carat, and fluorescence.

International Gemological Institute (IGI)

IGI ranks only behind IGA as a well-known and respected source for diamond grading and certification. IGA is headquartered in Belgium and has offices around the world. It is most influential in Asia.

From some, the complaint about IGA is that their grading system to too loose. They have been accused of grading a diamond above its real grade and then putting it on the market. However, IGA has its strong supporters who say that their ratings are totally accurate. These people will be very happy to pay more for a diamond that has been IGA rated. Because of what is essentially a split decision about IGA rating, there is little overall effect on diamond prices due to IGA ratings outside of the regions where IGA has the most influence. IGA grading includes clarity, color, and other surface features.

Gemological Institute of America (GIA)

GIA Certified Diamonds

GIA seal

The GIA was founded specifically to add transparency to diamond evaluation and pricing. This non-profit organization has become the industry standard for diamond grading and the processes by which grades are arrived at.

GIA is a pioneer in many of the technologies used to grade diamonds and has the strictest standards of any grading organization. Their grading certificates are considered the most reliable and consistent and the safest.

Our choice to grade a diamond is always GIA. If you have a very valuable diamond that was graded by one of the other institutions, we recommend in the strongest terms that you also have it graded by the Gemological Institute of America. The price difference between GIA certification of a diamond and certification by one of the others can easily be 15% to 25%.

We only carry GIA certified diamonds because of the reliability and consistency of their grading as well as the transparency of their grading process. GIA certification of a diamond provides you with a report that is a complete and accurate representation of your diamond. Your report will have a unique ID number. And, all diamonds of less than 1.0 carat are inscribed by laser on the diamond’s girdle. Laser inscription is optional for larger diamonds.

Getting to Know the GIA Report

GIA grading reports come in two forms. For diamonds less than 1.0 carat, GIA provides a diamond dossier. Larger diamonds receive a complete report of their grade. The biggest difference is that a full report includes a GIA diamond plot showing the precise locations of any inclusions.

Here is an example of a GIA report form.

example of GIA diamond dossier report for diamonds under 1.00ct

The first line is the certification date and the diamond’s unique GIA number.

The second line states the shape of the diamond and if it is a brilliant cut or not.

The third line states the dimensions of the diamond in length, width, and height.

Line four is the diamond’s carat weight to the nearest 0.01 carat.

The fifth line is the precise color grade

Line six is the exact clarity grade

The seventh line is the cut grade assigned if it is a round cut diamond.

Line eight is the diamond’s polish grade.

The ninth line is the symmetry grade.

Line ten is the grade for the diamond’s fluorescence.

The eleventh line describes inclusions responsible for the diamond’s clarity grade.

Line twelve is the exact inscription that is laser etched at the diamond’s girdle.

And the thirteenth line is for the gemologist to make comments about inclusions of diamond treatments that may affect the gem’s sparkle.

The diamond chart notes all angles and measurements that go into the cut grade. This will include table, crown angle and height, size of the girdle, depth and angle of the pavilion and culet and total diamond depth. The report will also include a reference table of GIA grading scales for reference.

You can verify the report by going to the GIA’s web page for checking reports and entering your report number.

How Do You Get Your Diamond GIA Certified?

To get a diamond certified by the GIA you need to send it to them. Most people have their jeweler handle this. It will cost money to have the diamond insured for approximate value and both sent to GIA and then back to you or the jeweler. GIA will charge in excess of a hundred dollars for analysis and grading of a one carat diamond.

It takes time to do a complete and professional diamond grading. If you want to know how long that will be, you can check with the GIA return dates page which will tell you when to expect your diamond back. The time required depends on which lab the diamond is sent to and the various quality features of the diamond. Even very unique gems will be graded and returned to you within a month and typically the turn-around time is around ten days within the USA.

When grading is done, GIA will send the diamond and its report or dossier back to you. There are instances when a gem in not certifiable and GIA will include an explanation if that is the case. The report will always contain the ID number which has been inscribed by laser on the girdle of the diamond.

GIA diamond grading report with all the diamond attributes as an example


GIA grading report with a diamond plot showing the inclusions mapping

The GIA diamond plot is an important part of the report. It tells you the style of faceting. Cushion cuts can have varying faceting and cutting styles and also variations in length to width ratio. The red and green marks on the plot are what show you the diamond’s inclusions, their sizes, and their types.

The definitions of the green and red markings and inclusion types are noted beneath the plot. All major inclusions that affect diamond grade will be noted on the plot. However, there may be small and relatively insignificant inclusions that are not recorded.