Each and every diamond is unique and has parameters that are both subjective (color, clarity, polish, etc.) and objective (carat weight, dimensions, etc.). A gem grading lab or institute analyzes and evaluates all the characteristics of a diamond using various tests and equipment. After verifying all the information, a report is created unique to that particular diamond. This document is commonly referred to as a dossier, certificate or report.
We strive to provide the most accurate information for each of our diamonds. Every diamond of 0.30cts and larger is independently graded by one of the major gemological laboratories - European Gemological Laboratory (EGL USA), Gemological Institute of America (GIA) and International Gemological Institute (IGI). American Gem Society (AGS) announced in 2011 that they will begin grading white synthetic diamonds 0.23 carats or more.
Differences between EGL and GIA
We are commonly asked why we use EGL by default, and not GIA. EGL has been grading synthetic diamonds since 2001 and GIA since 2007. They are both reputable and reliable labs, with GIA commonly having a perception of being more strict for mined diamonds. We have found the opposite to be true for synthetic diamonds, though are unsure as to the underlying reasons why.
Two of the more important factors when considering a diamond are color and clarity. EGL grades based on the average color throughout the diamond, which most resembles the color you see when looking at it in person. GIA grades color based on the single darkest point in the diamond, most likely because mined colored diamonds are exponentially more expensive, the more color they have. In early 2010, we sent the same batch of blue diamonds to both labs. In one example of color discrepancies, with three blues that are obviously different shades even to an untrained consumer, EGL graded them 'fancy light blue', 'fancy blue' and 'fancy intense blue' respectively, while GIA graded them all the same 'fancy intense blue'. We feel GIA's methodology does not provide the most accurate representation of color in the diamond, especially when buying online, without the ability to compare diamonds in-person side-by-side. On clarity, some diamonds were graded as VVS2 by EGL and "IF" by GIA, despite there being detectable inclusions at 10x magnification. Others have come back as an EGL SI1 and a GIA VS2. On the printed report, GIA does not list the specific clarity 1 or 2, just the written name ("Very Slightly Included" instead of VS1 or VS2).
Currently, no major lab provides a worded grading ("Excellent", "Very Good") for the cut of a diamond. Learn more about a diamond's cut here. For polish and symmetry, EGL's range is four categories from "Very Good" to "Poor", while GIA uses five categories "Excellent" to "Poor".
For the diamonds we have sent to both labs, the objective measures come back essentially identical. The subjective properties have sometimes been identical, but when they are not, we have found GIA typically grades color darker and clarity more clean than EGL.
For these reasons, we include an EGL report with all of our diamonds .30cts and larger. Some of our diamonds do include reports from both labs, and this is noted in their online descriptions, like with this diamond.
If you wish to have a diamond graded by GIA, or another major lab, we can do so for $200 per diamond. Please note that GIA typically takes four weeks to grade a synthetic diamond.
Below you can see a sample certificate for this 1.10ct round yellow diamond from both EGL and GIA to see the detail and differences:
We provide all the relevant details and measurements for each of our certified diamonds online. All details can be verified through EGL's online results. GIA does have an online lookup, but it does not include synthetic diamonds. Contact us and we can email you a scan of any report.