The Essential 7C's

Certificate Comparisons

The most renowned and trusted gemmological grading laboratories are the Gemological Institute of America (GIA), the American Gemological Society (AGS), the Hoge Raad voor Diamant (HRD), the International Gemological Institute (IGI), and the 2 versions of European Gemological Laboratory (EGL International and EGL USA). From these 5 laboratories, the 3 that set the standard are the GIA, AGS & HRD.(Search for GIA, AGS & HRD diamonds)

The GIA is widely regarded as the most reputable and recognized grading laboratory in the world, with the strictest standards. Founded by the creator of the GIA, The American Gemological Society (AGS) is a newer certification and markets itself around the fact that it offers an Ideal cut grade which is one higher than the Excellent from GIA and is as strict as GIA in every respect. The Hoge Raad voor Diamant (HRD) or Diamond High Council is almost as renowned worldwide as GIA but not as popular and it is 95% as strict in its grading. (Search for GIA diamonds)

BEWARE: Even though these are the 5 leading international diamond certification organisations their grading criteria do vary and are not equally strict. Please be aware of the differences when choosing your diamond (see below).

All the certificates differ slightly in layout, terminology and grading systems, with some including diagrams and symmetry or proportion grading and others being simpler. However, the two main grading aspects to consider when comparing certificates are colour and clarity, for their evaluations largely determine the price of a diamond and yet they are not consistently graded across the board. A colour grade, for instance, may differ in up to two grades (sometimes more) from one certificate to another and yet this is not always reflected in the price, so beyond understanding simply how colour or clarity grades work, it is essential to know how to interpret and compare them.

Beside the 5 types of certificates that we offer on 77Diamonds.com, there are a multitude of other types of certificates not always independent, such as “in house” certificates which are typically graded more generously even than EGL International certificates and which cannot be compared with independent internationally recognised certificates. 77Diamonds does not sell any in-house certificated diamonds.

Certificate Comparisons for Colour

Overall, the GIA tends to be the strictest on colour grades, and out of the other laboratories, HRD and AGS are the two that most closely adhere to the standards set out by the GIA. IGI and EGL USA tend to give one colour grade higher than GIA, and EGL up to 2 colour grades higher. So an F colour stone on a GIA certificate would most likely be the same on HRD and AGS, an E on IGI or EGL USA, and a D on EGL. Please refer to the table below for a more detailed comparison* (note: table is based on Seventy Seven Diamonds’ experience:

CERTIFICATE COMPARISON ON COLOUR GRADING

  Sold by 77DIAMONDS Not sold by 77DIAMONDS
  GIA AGS HRD IGI EGL USA EGL INT. In-house Certificates
White D D D D+ D+ D+ D+
White E E E D D D+ D+
White F F F E E E+ D+
White G G G F F E D
White H H H G G F+ D/E
Extremely faint yellow tint I I I H H F E/F
Very faint yellow/brown tint J J J I I G F/G
Faint yellow/brown tint K K K J J H G/H
Yellowish/brownish tint L L L K K I H/I
Medium to strong yellowish/brownish tint M M M L L J I/J
Strong yellowish/brownish tint N N N M M K K/L
Veyr strong yellowish/brownish tint O-P O-P O-P N N L L/M

*Note: Although not published anywhere, these differences are generally accepted within the diamond trade as correct and are also based on Seventy Seven Diamond’s experience.

Certificate Comparisons For Clarity

Again, with clarity the GIA is said to be the strictest, giving at least one grade lower than all other laboratories. The HRD adds its own clarity grade to the traditional scale, terming all stones with impurities invisible with a 10x loupe as "Loupe Clean." Because of this extra category, stones grades as IF or FL by the HRD would only receive a VVS1 from the GIA. The same applies for IGI, EGL and EGL USA, which would all grade between one and two clarity grades higher than the GIA, meaning that a VVS2 on a GIA certificate while the majority of AGS colour grades are equal to the GIA. Please refer to the table below for more detailed comparisons*.

CERTIFICATE COMPARISON ON CLARITY GRADING

  Sold by 77DIAMONDS Not sold by 77DIAMONDS
Clarity Description GIA AGS HRD IGI EGL USA EGL INT. In-house Certificates
100% Eye Clean FL/IF IF LC+ IF+ IF+ IF+ IF+
100% Eye Clean VVS1 VVS1 LC-/VVS1 IF-/VVS1 IF IF+ IF+
100% Eye Clean VVS2 VVS2 VVS2 VVS2 VVS1 IF+ IF+
100% Eye Clean VS1 VS1 VS1 VS1 VVS2 IF IF+
100% Eye Clean VS2 VS2 VS2 VS2 VS1 VVS1/VVS2 IF+
80% Chance SI1 SI1 SI1 SI1 VS2 VVS2/VS1 VVS1/VVS2
10% Chance SI2 SI2 SI2 SI2 SI1 VS1/VS2 VVS2/VS1
Not Eye Clean I1 I1 P1 SI3 SI2 VS2/SI1 VS1/VS2
Not Eye Clean I2 I2 P2 I1 SI3 SI1/SI2 VS2/SI1
Not Eye Clean I3 I3 I3 I2 I2 SI2/SI3 SI1/SI2
Not Eye Clean N/A N/A N/A I3 I3 I1 SI2/SI3

*Note: Although not published anywhere, these differences are generally accepted within the diamond trade as correct and are also based on Seventy Seven Diamond’s experience.

Click here to read more about diamond clarity.

Other Differences Between Certificates

The main other differences between the certificates lie in the differences between GIA, HRD and AGS. GIA gives separate grading for symmetry and polish which the HRD groups together under the heading of "finish." HRD also includes one clarity grade termed “Loupe Clean” which is not offered by the GIA. The AGS provides more information on the cut grade and offers one grade higher than the traditional poor-to-excellent scale of GIA, called "ideal cut," as well as a number scale from 0-10 on which to grade diamond cut.

Click here to read more about diamond cut.

Learn More

For questions or comments, please fill in the details below and we will respond within 24 hours.

Please fill in the details below and one of our experts at 77 Diamonds will call you back.


To request a consultation with one of our experts in our London showroom (only), please fill in the information below.