Geneva - The rare and flawless "Blue Moon Diamond" sold for $48.4m (R686m) to a Hong Kong buyer on Wednesday, setting a world record for a gemstone at auction, Sotheby's said.
The blue diamond stone was found in South Africa's famed Cullinan mine in January 2014. The seller was New York-based jeweller Cora International, according to Sotheby's.
The distinctive blue colour in diamonds is attributed to trace amounts of the element boron in the crystal structure.