At present, there are only diamonds. For GIA diamonds under one carat, the certificate number will be engraved on the waist of the diamond with a laser beam, which is convenient for the industry and consumers to identify whether the diamond is the same one identified by the certificate.

Is the code unique? Stolen jewels can be recovered by this number. But it is also difficult, because diamonds can be re-polished, and the code will be worn off, but diamonds will also become smaller and their value will be reduced, so diamonds over one carat generally have no laser code. At this time, it is necessary to compare the contents of the certificate with the diamond to identify whether the diamond is the same one marked on the certificate. The easiest way is to confirm whether the weight of the diamond is consistent with the certificate, because the weight of the diamond marked on the certificate is very accurate, and even if a diamond with similar grade is found, its weight cannot be exactly the same as that marked on the certificate.