If you’ve ever shopped for a diamond, you’ve probably heard of diamonds having laboratory grading reports. And perhaps you’ve wondered what helpful information these reports offer.
Every diamond shopper needs to understand these reports because differences in laboratory grading reports can dramatically impact how much you pay for your diamond.
There seems to be an endless list of acronyms for diamond grading laboratories, GIA, EGL, AGS, GCAL USGS, and IGI to name a few. For the sake of brevity we’ll focus on the top four: GIA, AGS, EGL, and IGI.
Gemological Institute of America (GIA) – Very Trustworthy
The oldest and largest diamond-grading laboratory is the Gemological Institute of America. Founded in 1931, the GIA developed the diamond grading system known as the 4 Cs (Cut, Color, Clarity, and Carat Weight), a system that is still used to this day. The GIA doesn’t sell diamonds, or other gemstones. They keep an arms-length distance from trading in diamonds to maintain their high standards, with zero conflict of interest. Their primary focus is education, teaching jewelers and the public about gemology.
American Gem Society (AGS) – Very Trustworthy
The AGS, or American Gem Society, meets the same standards as the GIA. The same person, Robert Shipley founded them both. The AGS offers a much more detailed report when it comes to cut. The report includes the standard grading for color, clarity, and carat weight, but deviates greatly when it comes to analyzing the cut of a diamond. The AGS looks at 11 different criteria to determine the cut grading of a diamond. It’s a 0-10 scale, with 0 being the best and 10 being the worst. The AGS report is used extensively by top jewelers and experienced clients who demand the highest standards in diamond grading. They know that cut is the most important of the 4 Cs when it comes to determining the value of a diamond.
EGL – Loose Standards, Soft Grading
From a purely commercial standpoint, some jewelers prefer an EGL graded diamond because it appears to present a better deal for the customer than an AGS or GIA graded diamond. However, their standards are not as strict, so an EGL stone may have the same grade on paper as GIA, but not actually be of the same quality or value as the GIA graded stone. A GIA graded diamond may retail for 50% more than an EGL stone with the same color clarity and carat grading. Yet, comparing EGL and GIA diamond reports is comparing apples and oranges. Always be sure you know which specific grading report you’re looking at, and how that report is viewed in the industry.
International Gemological Institute (IGI) – Loose Standards
Moving on to yet another grading option, the International Gemological Institute (IGI) is a lab that grades diamonds for large, mid-market chains like Zales and Kay Jewelers. They do have a niche in the industry, but the industry sees them as having looser standards than GIA or AGS. A higher-end jeweler typically will not deal with stones certified by the IGI.
De Beers International Institute of Diamond Grading and Research (IIDGR) – Very Trustworthy
Lastly, I would be remiss if I didn’t include the newest diamond-grading laboratory, De Beers International Institute of Diamond Grading and Research (IIDGR). De Beers has been the leader in mining and marketing diamonds for the past 100 years. They founded IIDGR to grade diamonds using modern and highly advanced technology to assure that every diamond they grade meets their sophisticated standards for quality and size.
I know that’s a whole lot to take in, but I hope you now understand the importance of grading reports in this complex field, and perhaps understand why the best jewelers pursue the equivalent of a PhD in gemology before confidently discussing these matters with authority and expertise.
Be sure to find a jeweler you trust when it comes time to learn more about these precious stones.