Synthetic-diamond makers received a boost in January when the Gemological Institute of America--the organization that invented the color, cut, clarity and carat diamond standards 50 years ago ...

Graff chairman Laurence Graff with the 102.79-carat Constellation, the world's largest D-colour, internally flawless round diamond, which was cut from Graff's Light of Letšeng 478-carat rough.

The current record for the most expensive diamond or any gemstone sold at auction is held by the CTF Pink Star, a 59.60-carat oval mixed-cut diamond auctioned at Sotheby’s Hong Kong in April ...