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 – International Gemological Institute (IGI), Gemological Institute of America (GIA) or European Gemological Laboratory (EGL USA). American Gem Society (AGS) does not offer reports for grown diamonds.
Differences between IGI, EGL and GIA
We are commonly asked why we use IGI and EGL by default, and not GIA. They have all been grading synthetic diamonds for over a decade. They are all 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. GIA grades fancy 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. 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).
For the diamonds we have sent to multiple 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 and IGI.
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 to six 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:
As part of the grading process, all diamonds .30cts and larger are laser inscribed as created, along with the grading report number for full disclosure. This inscription is not visible with the naked eye and does not affect the appearance of the diamond. It can be read with 10x or more powerful magnification.