JThomson Custom Jewelers

Diamond Certification

A certified diamond is a diamond that comes with documentation from an independent testing laboratory. The certificate gives measurements for the diamond, as well as diamond grades for each key characteristic. In addition, the certificate gives a detailed diagram of the diamond’s inclusions. (This will allow you to verify that the diamond you are holding matches the certificate).

Unless you are an expert on diamonds, you should not buy an uncertified diamond. Without this critical paperwork, you will never know if you are getting what you are paying for.

The most trusted name in diamond certification is the Gemological Institute of America (GIA). It has created the world’s most recognized and accurate system for grading diamonds.

You may also see certificates from the European Gemological Laboratory (EGL). This organization is not as well known as the GIA, but EGL certificates are also recognized and are accurate for grading diamonds..

If a certificate comes from a lab other than the GIA or EGL, there is a chance that the lab will not grade with the same strict standards, or that they will not give an unbiased opinion. (Be especially cautious of retailers who offer certificates that they produce themselves.)