Most expensive diamond per carat

According to Official Guinness Records,

The record price paid per carat is $4,028,940 (£2,665,890) for Blue Moon of Josephine, a 12.03-carat cushion-shaped internally flawless fancy vivid blue diamond, which sold for US$48,468,158 (CHF 48,634,000;£31,939,478;€45,238,998), including commission, at Sotheby's auction, in Geneva, Switzerland, on 11 November 2015. At the auction, the blue diamond, the first diamond or gemstone to surpass the $4 million mark per carat, also set world auction records for any diamond, gem or jewel.Previously called Blue Moon, the internally flawless diamond was renamed Blue Moon of Josephine by Hong Kong tycoon Joseph Lau, who bought the gem for his daughter Josephine.The diamond was found in the Cullinan mine in 2014.

For a complete list of 2015 records, please visit 2015 Guinness Records in Switzerland.

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