World's largest blue diamond, 'exceptionally rare' at 15 carats, sells for $57 million - USA TODAY

The world's largest blue diamond, "The De Beers Cullinan Blue" now has a price to match its rarity. It's described as "a once-in-a-generation stone."

The world's largest blue diamond now has a price tag to match its rarity.  The 15.10-carat diamond, called "The De Beers Cullinan Blue," sold for $57.5 million Wednesday in an auction at Sotheby's i… [+1297 chars]

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