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Diamond Grading Certificates: Are They All Created Equal?

When purchasing a diamond, it is extremely important that the specifications of your selected diamond are verified by a third party (whether the diamond is a Kimberfire diamond or is purchased elsewhere). For insurance purposes, for your peace of mind, for future value, there are many reasons why this third party certificate is critical. Which laboratory can you trust though?

Making the (Diamond) Grade

There are many diamond grading laboratories out there, but only a few with well-established reputations. Often, smaller labs are for-profit entities with various conflicts of interest. To ensure you receive an objective, reliable certificate, my recommendation is to always stick to the big guys. Diamonds carrying certificates from the larger grading laboratories may come with a small premium as the international labs charge more and their closest office may be out of town, but it is worth the nominal cost for a certificate you can trust and rely on.

GIA vs. EGL Diamond Grading Certificates

The most notable of these labs, and the certification body I stand behind, is the Gemological Institute of America (“GIA”). The GIA is widely known to have the most consistent and strict grading process out of any lab out there. Independent studies have shown GIA to be strict, consistent and, most of all, ethical when it comes to their processes and resulting grades.

Other well-known and reputable labs are the American Gem Society (“AGS”), HRD Antwerp and the International Gemological Institute (“IGI”).

On the opposite end of the spectrum are the labs that are known to be consistently inaccurate or lenient. The most well-known example of these lenient laboratories is the European Gemological Laboratory (“EGL), particularly their Hong Kong and Israel offices. In the trade, diamonds with these certificates sell at a substantial discount to the others. As a result, when passed through to the retail consumer, EGL certified diamonds may come off as being sold for an unbeatable price. As is the case with most too-good-to-be-true diamonds, EGL certificates are known in the industry to typically be two colour and/or clarity grades off, compared to the more-reputable graders. To be confident in what you are buying, I always suggest sticking to the more reputable labs mentioned above.

Proof Is In the Independent Studies

For more information you can view a recent study on the accuracy of the various labs, conducted by a major industry organization. In conducting this study, the team at Rapaport sent the same ten diamonds (of various sizes and qualities) to six different labs for grading. They found significant differences between laboratories grading the same diamond… no two diamonds are alike, and neither are their grading certificates apparently!

The six labs tested by Rapaport included the GIA, IGI, HRD, EGL USA, EGL Israel and EGL Hong Kong. Rapaport found the GIA to be the strictest of the group, thus setting the benchmark. EGL Israel and EGL Hong Kong were found to be one to two clarity and/or colour grades more lenient (if not more) in quite a few instances. This same trend also applied to cut and fluorescence grading by the EGL laboratories.

So Which Certificate Do YOU Trust?

While a diamond accompanied by an inferior diamond grading certificate may appear to be a bargain – the recommended course is to stay away. You can always purchase a GIA graded diamond, for the same price, that on paper is one to two clarity grades lower than the poorly graded diamond. You will walk away with the same product at the same price, but will then have the confidence of knowing that the diamond you purchased will be appreciated as such by anyone who may evaluate it in the future.

I’m always happy to answer any questions in the comments below! And, as usual, please share this article if you know anyone who may benefit from reading it.

6 replies
    • Jonathan Goldberg
      Jonathan Goldberg says:

      Hi Adrian. Thank you for reading! It’s very difficult to say without actually inspecting the diamonds. In the chance that they are accurately graded by EGL then you will definitely be adding value by obtaining a GIA certificate. If they were graded more leniently than GIA however, then you should likely expect downgrades in both colour and clarity. It’s hard to say how this will impact the value without knowing the extent of this discrepancy and who you will be selling it to (personally I do not feel comfortable representing diamonds to my clients that are graded by anyone other than GIA or AGS). That being said, barring the value argument, if you’d like to know with certainty what quality your diamonds are then I definitely recommend obtaining GIA certificates so that you know what you are holding. This way, if you ever decide to sell them, you can feel confident in how you are representing your diamonds. I hope this helps!

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    thomas oak says:

    Hi can I get a second certification on a gem stone or is it worthless after getting a EGL certification I bought a very large emerald and it come to me with egl certification so my question is can I fix this issue the stone say’s its species is beryl and it is 1385ct oval cut cut is poor I can see that with no training its green I got a guess at $1,300,000 value but a more credible certificate would hold its value better then it’s in my best interest to get one if it’s a possibility?

    • Jonathan Goldberg
      Jonathan Goldberg says:

      Hi Thomas, thank you for your question! You can always submit your diamond to another lab for evaluation. There shouldn’t be any problem with this. Although, if your gem is laser inscribed by a lab already then it will always be tied to that certificate as well. If there is no inscription then there really isn’t anything connecting it to a lab if looking at the gem itself. Especially if you feel the current certificate may be overstating the qualities and value of the gem, then a more strict and credible certificate will likely provide any future buyer with greater assurances as to what you are providing. I hope this helps!

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    Yan Mil says:

    after a thorough look into the subject, i searched for a lab that would give the GIA equal results. it was found that SGL Lab from Switzerland brought the most similar results to GIA! the Swiss seem to be proving their quality again…


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