Buying Certified Diamonds
The diamond certificate is essential proof of what you've bought.
A diamond certificate is a report created by a team of gemologists, also known as a diamond grading report, diamond dossier or a diamond quality document.
A diamond certificate is a "blueprint" of a loose diamond. It tells you the diamond's exact measurements and weight, as well as the details of its cut and quality. It precisely points out all the individual characteristics of the stone. It will also confirm to that the stone is indeed the genuine article. Certificates also serve as proof of the diamond's identity and value.
A certificate is not the same thing as an appraisal. A certificate describes the quality of a diamond, but it does not place a monetary value on the gem.
There are many diamond labs that issue certificates, but the Gemological Institute of America (GIA) and the American Gem Society (AGS) are the two most widely regarded and recognized diamond grading labs in the world.
To learn more about GIA visit their website 
Aside from the more obvious terms of cut, colour, clarity and carat weight, some typical terms diamond certificates report on include the following:
About Buying Diamonds is a comprehensive guide explaining diamond characteristics like cut, colour, clarity & carat, as well as the different diamond shapes and types of diamonds. You can learn what to buy for your diamond jewellery needs such as diamond rings or diamond bracelets and how these grades will affect diamond prices. The process of buying diamonds online may be daunting to some, so throughout this site we offer advice and information on buying all types of diamonds including loose diamonds and wholesale diamonds and the reasons why you should always buy certified diamonds.