Understanding Diamond Certificates

Our gemologists explain what diamond certificates are and why they matter.

Understanding Diamond Grading Certificates

What Is A Diamond Certificate?

Diamond Certificates, also called Diamond Grading Reports, are documents produced by gemologists in Diamond Grading Laboratories. Each report contains the key characteristics of the diamond including the 4 Cs - Carat weight, Clarity, Color and Cut. It is also a representation of the diamond's proportions and sometimes a plot diagram of any inclusions the diamond exhibits.

Who Certifies Diamonds?

There are hundreds of Diamond Grading Laboratories worldwide, and in truth anyone with a knowledge in diamonds could set up a Diamond Grading Laboratory. It is also worth noting that to date there are no international bodies set up to control these laboratories. In fact, even well respected international grading labs come up with different results - just look at this study completed by Rapaport; Grading The Graders.

The most important characteristic of a gemological laboratory is that they are entirely objective regarding the diamond grading they perform. This means that they must be independent from any commercial interests; for example, if a laboratory is in anyway affiliated with a retailer, wholesaler or diamond trader, there could be problems in terms of the objectivity of their assessments.

Get An Accurate Grade

Diamond grading is very subjective as it is the personal opinion of the highly skilled gemologist who is assessing the stone. Because of this however, one laboratory’s grade of a particular diamond may not match that of another grading the same stone. To avoid this, it is important to stick to a reputable Gemological Laboratory in order to get an accurate

grade on your diamond as most reputable laboratories will have a number of different people grading a single stone and this will ensure consistency. One must always be conscious of the fact that diamond grading is an art not a science, and is based upon the opinions of trained and skilled gemologists.

The Top Gemological Laboratories

myGemma believes GIA, EGL-USA, IGI and AGS to be the most highly regarded gemological laboratories in the diamond industry today.

GIA logo


The Gemological Institute of America is the world’s longest running and most respected gemological laboratory. Established in 1931, GIA created the 4C’s and the International Diamond Grading system that is widely used today. The GIA is a non-profit organization, known throughout the industry as impartial and independent.

Located in major gem and jewelry centers around the world, GIA laboratories are staffed by expert diamond graders and gemologists. The level of expertise as the GIA means that they really do set the standard for grading practices worldwide.

The GIA not only grades gemstones, it also trains and educates thousands of gemologists through graduate programs around the world – a qualification from them is regarded as top class.
GIA examines over 2 million diamonds, colored stones and pearls every year and has graded some of the world’s most famous diamonds, including the Hope (45.52 carats), the Steinmetz Pink (59.60 carats), the Taylor-Burton (69.42 carats), the Allnatt (101.29 carats), the De Beers Millennium Star (203.04 carats), the Centenary (273.85 carats), and the Incomparable (407.48 carats).

Do You Have A GIA Certified Diamond?

Having a GIA Certificate can increase the value of your diamond when you come to re-sell through a company such as myGemma. We put a lot of trust in a GIA report as we feel they are the most accurate in the marketplace.

Send us your certificate and get a very accurate initial valuation from myGemma;



EGL-USA has been running for over 3 decades. Located in New York, they produce a variety of reports. It also participates in Gem testing, research and Lab analysis. Here at myGemma, we find EGL USA grading reports to be quite accurate across the board. Their website can be found with this link;



The International Gemological Institute (IGI) was established in 1975, and is the oldest Gemstone laboratory in Antwerp. They have a further 16 offices worldwide which outnumbers any other laboratory. They also run the IGI School of Gemology in four of their worldwide offices. The IGI created the Heart and Arrows certificate with worldwide recognition, and offers reports on diamond set jewelry, rather than just loose stones. Their website can be found with this link;



The American Gem Society was founded in 1996 and is known as one of the first labs to offer diamond grading reports on fancy cuts, including princess, emerald and oval. They also pioneered the Ideal cut grade for the round brilliant diamond.

Why Have A Diamond Certificate?

In short, the information found on a Diamond Grading Report (if from a reputable and internationally recognized laboratory) allows the diamond to be identified and traded easily throughout the world.

Having the diamond’s characteristics documented by a reputable source, such as GIA, enables a diamond expert to assess the stone without actually seeing it. The report can tell the expert most things that they

need to know about the stone, from the precision of its cut through to the position of its inclusions. All these factors help determine the price of the diamond.

It can also help a consumer when they come to buying a diamond, as the report allows them to make a direct comparison with other diamonds, enabling them to buy a diamond most suited to them at the best price.

How Does A Certificate Help Me Sell My Diamond?

Certificates contain most of information necessary to get an accurate value of your diamond. They generally incorporate information on the most well-known aspects of a diamond, the 4C’s – Carat weight, Cut, Color and Clarity. Most certificates and reports also have other information diamond experts can use to help them analyze a diamond’s attributes without actually seeing the diamond, such as proportions and fluorescence.

Futhermore, having a GIA Certificate (rather than a certificate from another laboratory) can actually increase the value of your diamond when you come to re-sell through a company such as myGemma. Because they set the global standard and are accepted worldwide as the benchmark in diamond grading, we put a lot of trust in a GIA report as we feel they are the most accurate in the marketplace.

Other Diamond Certificates

Other Diamond reports from reputable laboratories can also add value when you come to re-sell your diamond. All reports contain some accurate information such as an exact weight, otherwise an estimated weight would have to be calculated if the diamond is set in jewelry. Even if the certificate doesn’t have a Cut Grade, with the diamond’s proportions, table size, symmetry and polish, a diamond expert can analyze these proportions to determine how well the diamond is cut. This can have a huge impact on the value as an ‘Excellent’ cut diamond can carry up to a 30% premium.

Where Can I Sell My Certified Diamond?

Pawnbrokers & Gold Buyers do buy diamonds as well as precious metal. They are not diamond experts of course, but with a certificated gemstone, there tends to be less room for error. If they have a retail outlet they may be able to sell it, or they could sell it to a diamond recycling company such as myGemma.

Jewelry Retailers may also buy certificated diamonds, as the certificate adds the reassurance of the diamond’s attributes, enabling them to buy an item they feel is saleable. They may also offer to put the item into the shop window for you, and when it sells, they will take a commission from the sale.

Auction Houses are often used to sell antique or ornate second hand jewelry. They have detailed knowledge regarding second hand jewelry and diamonds and can advise on what value the piece may be worth. Should you choose this path, it is worth noting that upon completion of the sale, the Auction House will take a sizable percentage of the sale price and some auction houses even charge just to market the item as well. This can also be a time consuming process, as the diamond will have to be catalogued before it can be sold.

Online Diamond Buyers such as myGemma make the process fast, simple, secure and free. Send your Certificate to our expert team now to receive a no obligation initial valuation.

Diamond Trends

myGemma trades in the diamond markets daily and they understand which diamonds are in high demand at any given time. In the diamond market, certain diamonds with specific characteristics trade much faster than other diamonds. These trends are regularly changing; having a report means the diamond can be purchased and then recycled back into the market place very quickly, meaning a higher price is going to be paid for a diamond with a report because it is accurate and trusted within the diamond industry and therefore easier to trade.