GIA Certification — What Makes It So Great?

Cream of the Crop

Fact of the matter is, darling, that different retailers extoll the benefits of different grading labs for a variety of reasons, including that they’ve paid to have their stones certified by one and thus want to convince you it’s the best lab out there. It happens. But there’s no getting around the fact that the Gemological Institute of America (GIA) is, hands down, the gold standard in diamond grading. 

Why? Well, every lab out there (or, at least any worth noting) is using the good ol’ 4Cs diamond grading system. But GIA invented the darn thing. Established in 1931, and continuously operated as a non-profit, GIA is considered the most consistent and objective independent diamond grading lab. That said, GIA certifications can sometimes fetch a slightly higher (about 10%) price tag than other lab-graded stones because of this great reputation that adds perceived value to the stone.

GIA Diamond Grading Reports

GIA certifications come in a few different flavors, so it’s good to know what you’re looking at (and every lab has slightly different names for their certificates). For natural diamonds, there is the Diamond Grading Report (DGR) that includes an assessment of the 4Cs – Color, Clarity, Cut, and Carat Weight – along with a plotted diagram of the diamond’s clarity characteristics and a graphic representation of its proportions. For standard round brilliant cut diamonds falling in the D-to-Z color range, the report also includes a GIA Cut grade. There is also what’s called the GIA Diamond Dossier® that can be issued for diamonds weighing 0.15 – 1.99 carats. This leaves out the full clarity plot, but will always include a microscopic laser inscription of the GIA report number for easy identification (a DGR can be issued without an inscription, but these days is more rare).

GCAL Guaranteed Diamond Grading Certificate

A relatively new player in the diamond grading game, GCAL (Gem Certification & Assurance Lab) was established in 2001 in NYC and offers a “money-back guarantee” on their grading certificates. Again, they offer several different versions of their certificates, but the most common is the Guaranteed Diamond Grading Certificate, which includes many of the same basic stone details as GIA, but no full clarity plot. Instead, GCAL offers Gemprint, an optical fingerprint of your diamond, along with actual photomicrograph images of the top (crown) and bottom (pavilion) of the stone.

In addition, and this is where GCAL’s specialty lies, their certificate provides an in-depth light performance profile that captures the brilliance and symmetry of each diamond, complete with visual representation. Their Guaranteed Express Grading Certificate, similar to GIA’s Diamond Dossier, is an abbreviated version that leaves out the light performance details. GCAL offers the same versions for lab grown stones, again, with the “lab grown” laser inscription on the diamond’s girdle. Overall rating? High. GCAL’s grading standards and consistency are on par with those of GIA, they’re just a bit newer to the game, and there are fewer stones out there with GCAL reports so far. Some retailers also offer the two in conjunction as a double-certification if you’re really into it.

IGI Diamond Reports

The IGI, or International Gemological Institute, stakes their reputation on being the most global of the big-acronym labs, with 20 locations around the world. This creates accessibility and access to high quality, graded lab grown diamonds. IGI is less strict than some other institutions when it comes to color-grading natural diamonds, so we tend to lean on them for lab grading only!

The IGI Diamond Report does include a clarity plot but does not include proportional diagrams or light performance measurement. Where IGI has beaten others to the punch is in lab-grown diamond grading. Across the globe, IGI began actively grading lab-created diamonds ahead of the pack and thus you’re going to find more lab grown diamonds with full IGI certificates. The IGI Laboratory Grown Diamond Report provides the same information as the IGI Diamond Report along with, you guessed it, a “lab grown” inscription on the diamond’s girdle for clear identification.

AGS Diamond Grading Reports

Founded in 1934 by the same folks behind GIA, The American Gem Society (AGS) is revered for its proportion-based cut grading system. Along with GIA, AGS is one of the most reputable diamond grading labs out there, however their consistency on clarity grading is often considered a bit more iffy than GIA’s. 

For natural diamonds, AGS offers three different report options. The Platinum Diamond Quality® Document includes all the standard good stuff, plus a full clarity plot and a light performance map, called an ASET® map, which captures the specific brightness and contrast of each diamond. The Diamond Quality® Report Series leaves out the ASET® map, and the Proprietary Light Performance Diamond Quality® Document, which is pretty much the same as the Platinum but offered for branded diamonds with a branded logo.

EGL Diamond Reports

The European Gemological Laboratory, a member of the EGL USA Group, has been around since the late 70s, but due to organizational changes, suffers from a lot more inconsistency in their grading and report styles — including an up to two grade difference from more reputable labs. For obvious reasons, this isn’t ideal, and in general we don’t recommend certificates from EGL.

Making the Grade

It should be noted that, in general, lab grown diamonds have only recently started to receive reputable diamond grades, which means that more inconsistencies may happen and fewer certificates may exist. You can always, however, request that a stone be sent to the lab for a certificate if it doesn’t yet have one, for a fee of course. Any reputable jeweler should happily oblige, but keep in mind that if you’re shopping for more unique things like antique cuts, rose cuts, or salt-and-pepper diamonds, certificates are less the norm, so don’t be too surprised to not find one.