The price of a diamond varies 100s of dollar just with a simple change in the
- Cut
- Clarity
- Color
- and Carat
You can find a list of GIA certified diamond companies using Google search. Search for the query "GIA Loose Diamonds"
Today there are lot of companies who have come up with lab generated diamonds which looks very close to the naturally extracted diamond which is available for 3 times lesser price then the real diamond. Labs like GIA, AGS provide detailed verification service for every piece of diamond. Again, it is important for one to know that GIA does not provide a Certificate 1 and it only provides a Lab Report.
List of Widely Accepted Diamond Lab Reports/Certification Agencies
1. http://www.gia.edu/nav/footer/copyright-trademark/index.html#certification