Posted on February 3, 2016 by

Understanding a GIA Certificate

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When you make a colored diamond jewelry purchase, chances are your precious new jewel will be accompanied by a diamond certificate, oftentimes a GIA certificate, alternately known as a ‘colored diamond report.’ If not, you will want to make sure you can have your diamond certified to ensure that you’re actually getting what you believe you have bought. The GIA, or Gemological Institute of America, sets the standard for issuing diamond certificates because they are an independent gemological laboratory whose grading is wholly accurate, objective and strict. On the other hand, other labs tend to have much more lenient grading standards and usually issue better grades for low quality diamonds than they should really receive for the primary purpose of making sales.


How to Read a GIA Certificate


GIA Certificate for Fancy Colored Diamonds

This is what a GIA certificate for colored diamonds looks like.


Basic identifying details

Once you have your GIA certificate and proceed to make sense of the technical jargon printed inside, you’ll see that all the information detailed on your colored diamond report is comprehensive and unique to your diamond. In the left-hand column of the GIA certificate, you’ll see the date the report was issued, the report number – a specific series of digits used to identify your diamond in case you should need your diamond report reprinted and to allow you to verify the report directly on the lab’s website – and the shape and cutting style, as well as dimensions of your diamond captured to the nearest hundredth of a millimeter.


Four Cs

The next section of the GIA certificates details the “Four Cs” (or, in the case of colored diamonds, the “Three Cs”): carat weight (captured to the nearest hundredth of a carat), color grade (intensity, along with modifying color(s) if any, and base color), clarity (based on number and type of flaws known as ‘inclusions’ and blemishes). At this time, GIA does not give colored diamonds cut grades, which comes as no surprise since it is color that is of utmost importance where fancy colored diamonds are concerned.



Beneath the “Three Cs,” there is a proportions diagram, illustrated as a profile view, which indicates the specific table and depth percentages of the stone you own. The girdle thickness and absence (or in some cases, presence) of a culet are indicated in the proportions diagram as well. The absence of a culet, indicated as ‘none,’ is generally preferred because a large culet tends to result in a diamond with diminished beauty. The optimal girdle thickness is a range spanning thin to slightly thick to allow the diamond to appear larger in a face-up position.


Polish, Symmetry, Fluorescence and Comments

The final section of the left-hand side of a GIA colored diamond report are polish, symmetry and fluorescence grades. Polish refers to the smoothness of a diamond’s surface. Diamonds with excellent polish grades will have reflections that appear sharp and transmit light seamlessly. Symmetry refers to the particular alignment of the diamond’s facets in relation to each other. As you might conclude, both are of vital importance because they help determine how the diamond will look. Fluorescence is the strength and color a diamond glows in the presence of ultraviolet (UV) light. The presence, or absence, of fluorescence remains a subjective issue. Any laser inscriptions and comments about your diamonds are noted just below the fluorescence grade on a GIA colored diamond certificate.


GIA Colored Diamond and Clarity Scales

In the center column of a GIA colored diamond certificate, GIA includes a ‘GIA Colored Diamond Scale’ to illustrate the extent of fancy color grades and how they relate to each other. This diagram is particularly useful to give a better understanding of how color is derived in fancy colored diamonds. Adjacent to the colored diamond scale is a clarity scale indicating a range of eleven possible clarity grades from best (Flawless) to worst (I3).


Unique Clarity Plot

Below the colored diamond and clarity scales is a diagram of your diamond’s clarity plot. Think of the clarity plot as your diamond’s fingerprint, detailing the particular inclusions and blemishes that exist in your diamond. External flaws, or blemishes, are marked in green whereas internal flaws, or inclusions, are in red.


Security Seals and Declarations

The right-hand column of a GIA diamond certificate contains security seals and declarations to establish the authenticity of the certificate. There is also a QR code you can scan with your smartphone or tablet to verify the authenticity of your certificate on the issuing lab’s website.


Shop our vast collection of GIA-certified fancy colored diamonds!

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