The Blue Moon of Josephine is a 12.03 carats (2.406 g) blue diamond, described as flawless by experts, that was discovered in South Africa in January 2014 and was sold at a Sotheby's auction in Geneva in November 2015 at a record-setting price of $48.4 million (43.2 million Swiss francs plus fees).

[1] The diamond is the largest cushion-shaped blue stone classified as "fancy vivid" ever to appear at auction.

[2] The "Blue Moon" sale, according to David Bennett, the head of Sotheby's international jewellery division, set a record for the highest-ever price per carat and it made the diamond both the most expensive jewel ever sold at auction and the world's most expensive diamond, regardless of color.

[1][2] The diamond was bought by the Hong Kong billionaire, and fugitive convicted felon, Joseph Lau Luen-hung, who named it for his seven-year-old daughter, Josephine.

The diamond was expertly conceived and meticulously analyzed from rough to polished by George Togholian, formerly of Cora International.