It’s prepared in an independent laboratory by certified gemologists. A diamond grading report should have your diamond’s 4 Cs: (color, clarity, cut, carat weight). It will describe the diamond’s shape, round, princess, trillion, and so on.
Measurements should include: table and depth percentages, grade the polish and symmetry.
Characteristics should be included: like fluorescence, graining, and imperfections.
Some certificates will include an estimated replacement value of the stone for insurance purposes.
Finally, the certificate should include a detailed sketch of the diamond.(diamond plot)
A certificate or diamond grading report assures a diamond buyer of the quality, and authenticity of their stone.
This will provide the stamp of authenticity you’ll need to get a fair price if you should resell your gem.
It is also often required if you are going to insure the jewel. The certification process should take no longer than two working weeks, and the price per gem varies according to weight.
Most labs charge $75 to $125 pre cart. A certificate (diamond grading report) may not increase the value of a particular piece; the gem cannot be undervalued or have its authenticity questioned.
That makes the certificate an important document. The only document that travels with the gem is the certificate just as a birth certificate stays with us forever so does the diamond certificate.
This stays with the stone forever. So you are asking how can I get one of these certificates?
Some dealers will promote their own certification process, and in some cases this would be fine, we recommend that if you want to use a stores certification make sure that there is an on site certified gemologist.
Update: To say that a certificate will not increase the value of a particular piece. That isn’t what we’ve seen over the past four years since I wrote this blog post. GIA certified diamonds fetch a much higher price than any other diamond. The certification from GIA is at a premium you can expect to pay more for any diamond you are buying certified by GIA. There is a huge demand on GIA certified stones since September of 2014 when RapNet stopped listing EGL grading reports.