Two rare diamond rings that sold this week, one of which was the most expensive ever to be auctioned, were graded by a Carlsbad nonprofit organization.
First on Tuesday, the 15.38-carat “unique pink” diamond went for $28 million at a Geneva action.
Then, the “oppenheimer blue” sold for $57.5 million the following day at Christie’s Geneva, making it the most expensive diamond to ever be auctioned.
The Carlsbad-based Gemological Institute of America, an organization that protects the public trust in gems and jewelry, graded both diamonds.
The “unique pink” mined near the Kimberley area of South Africa and touted for its clarity and pure structure, was the star lot in Tuesday's Geneva auction.
Blue diamonds are thought to be the rarest and most sought-after color. The “oppenheimer blue” was owned by Philip Oppenheimer, the late chairman of the De Beers diamond-marketing group.
The Gemological Institute reports that only one in 10,000 diamonds has a fancy color, and of those, only a handful are given top grades.