From a standpoint of accuracy and consistency, the consensus of the experts is that EGL certification is not as reliable as diamond certification done by AGS or GIA
. As a result, diamonds marketed with EGL reports are significantly discounted relative to diamonds with reports from AGS Laboratories (AGSL) and GIA.
Diamond certification is part science and part practiced skill, but it is also a business. There appears to be a fundamental business reason that EGL reports are considered by the diamond and jewelry industry to lack some credibility. “EGL” is network of independent labs lacking central control. What is generally referred to as “EGL” is a combination of European Gemological Laboratories International and EGL USA Group, somewhat related but distinct entities. GIA, while having multiple labs worldwide, is a single business entity with unified practices and philosophy. Likewise, AGSL
is a single, stand-alone laboratory with strong leadership and focus.
Without unified philosophy and diamond grading practices and procedures
that are designed to produce reliably consistent results in line with industry standards, laboratories fall short of their core purpose. This has evidently been the problem for EGL and the reason their reputation is not at the level of AGS or GIA. It is felt that certain of the EGL labs grade more accurately and consistently than others, but the perception of the market paints them with the same general brush.
As a result of the above factors, buyers generally assume that the diamond reported in an EGL report is at least a color and clarity grade lower than were it graded by AGSL or GIA, and prices are generally predicated on that assumption. The problem is that there have been cases where the differences are greater than one clarity and color grade, so even that formula is not comforting enough for many buyers. Many diamond dealers avoid offering EGL graded stones altogether. Some will only offer diamonds with EGL certificates from certain labs. Consumers shopping for high end diamonds have a strong preference for AGS and GIA graded diamonds. In terms of EGL vs AGS, buyers seeking diamonds of the finest cut quality prefer AGS for the comprehensive, detailed and stringent analysis done at the AGSL. Is AGS or GIA better? For those interested in top cut quality and light performance, an AGSL report provides much greater assurance. AGS Laboratories has developed the only scientifically vetted system of grading light performance in diamonds.
A unique aspect of EGL certification is the use of the SI3 grade which is not part of the clarity grading system that was developed by GIA and used by AGS and most other labs worldwide. Therefore, even if graded accurately and consistently, by design many EGL reports will result in higher clarity grades for diamonds falling in the top of the GIA Imperfect range.
In light of the foregoing, it is easy to see why the answer to question “Is EGL certification as good as AGS or GIA?” is a pretty clear “no”, even though EGL reports are widely available in the marketplace. The reason for the popularity of EGL reports is no doubt in part related to the perception on the part of diamond dealers that EGL grading is more lenient. EGL has been very “trade friendly” in other ways as well, with service costs and turnaround times better compared to GIA and AGS.
From a consumer standpoint, a balanced assessment of this topic should include the recognition that a report does not change the diamond. If it is beautiful to the eye of the beholder, and competitively priced, it may not matter to a buyer whether it is technically an H color or a J color, an Si1 clarity or an I1, an EGL or GIA report. But for modern consumers utilizing the internet in their search for the best values on high quality certified diamonds, it is critical that they be able to compare “apples to apples”. And for those diamond shoppers AGS and GIA reports are indispensable.