What is a Certified Diamond?

Buying a certified diamond means that you are buying a stone with a full grading report or a dossier. A diamond dossier consists of the exact measurements of the diamond and the “4 C’s”: carat, color, cut, and clarity. A diamond certificate will precisely identify the individual characteristics of the stone and help with its identification.

There are a number of labs that will provide a grading report, but the quality of the reports varies from lab to lab. Some private labs tend to skew the report in favor of the seller while others are too lenient in their grading.

It is important to note that having a diamond certified by a specific lab does not bolster the stones value. The value of the diamond depends on its physical attributes, not the report. If one of the private labs certified the diamond as having a certain set of desirable attributes and another, more reputable facility gave it a lower grade, the diamond will actually cost less in the long run.

Lenient grading by actual grading labs isn’t the only thing that you have to worry about when it comes to the certification of your diamond. Forged diamond certificates are extremely prevalent especially when you purchase from private parties. Diamond certificates are easy to forge and almost anyone who has access to a digital camera and a laser printer can do it. The good news is, the fakes are pretty easy to when you know what you are looking for.

The following is a list of red flags that you should pay attention to:

  • The certificate is using a name of a laboratory that doesn’t actually exist. You can determine if a lab exists by simply performing a google search.
  • The quality of the report seems low or sloppy.
  • The dossier uses the wrong terminology. Consult our Diamond Glossary for more help.
  • The certificate is from a small or no-name lab. Although the certificate is legitimate it should be considered as an opinion only. As mentioned previously, smaller labs have a tendency of being more lenient with their grading. Some very small labs will outright lie about the quality of the stone.
  • Certificates with USGL (United Service of Gemological Laboratory) as the name. Although the company is real, they do not certify origin of the stone which means you could be getting treated stones.

In order to avoid falling into the grading tap, we recommend that you know exactly who certifies your diamond and the reputation of the laboratory.

Gemological Institute of America (G.I.A.)

G.I.A is an institute dedicated to research and education in the field of gemology. G.I.A. certification is considered to be the best and most accurate. G.I.A. uses two types of reports. The first one is a full G.I.A. document that outlines a full description of the diamond as well as a detailed plotting of the grade-setting clarity. The second report is a dossier that has complete individual details of each diamond being graded. Both reports can be identified by a unique number that is laser inscribed on the diamond and can only be seen at x10 magnification.

Although G.I.A. certified diamonds may appear to be more expensive at first glance, they are actually cheaper in the long run. Some dealers and jewelers do not use G.I.A. because of the lower quality diamonds that they are selling. These diamonds would get a lower grade with G.I.A. making them cheaper. In an attempt to raise the price of the diamond, some jewelers take their low quality diamonds to lenient labs.

It is also important to note that a G.I.A. appraisal is not the same as a G.I.A. certificate. The certification process is significantly more involved and more thorough than an appraisal.

International Gemological Institute (I.G.I.)

Although not as highly regarded as G.I.A., I.G.I. grading report is pretty reliable and usually unbiased. I.G.I. is one of the largest independent grading and appraisal organizations in the world that staffs over 500 gemologists and scientific technicians worldwide to examine and appraise diamonds, gemstones, and jewelry. Much like G.I.A., I.G.I. provides a detailed report with every one of their certificates as well as offers laser inscription services. I.G.I. stores all of their grading reports in a specialized and searchable database making it easy for you to find the records for your diamond.


A US based lab that can provide detailed reports of diamond and gemstone quality and treatments. EGL is also able to certify set stones. Beware that although EGL USA is considered to be a credible albeit somewhat lenient lab, EGL Europe, Israel etc. may or may not be as reliable.

G.S.I. (Gemological Science International)

Is a fairly young gemstone and diamond grading laboratory that offers its services to the jewelry industry. Both professional jewelers and jewelry buyers can request a diamond and gemstone grading report to be done at a fairly low cost. G.S.I. is the fourth on our list of reliable labs mostly because their results can be skewed. We would recommend taking a G.S.I. certification as an opinion, not as an official grading report.

This list is by no means exhaustive. There are hundreds of different labs and institutes with various degrees of credibility to their grading reports. Remember, it is better to have a grading report than not. Always take a diamond certificate as an opinion until you know the reputation of the certificates provider.