The 493-carat "Letseng Legacy," the world's 18th-largest diamond, has sold at auction for $10.4 million.

Gem Diamonds Ltd. and the Government of the Kingdom of Lesotho, the owners of the Letseng le Terai Mine from which the diamond was procured, have announced Graff Jewellers' manufacturing arm, Safdico, as the winning bidder.

London-based Graff Jewellers was also the winning bidder of the Letseng mine's "Lesotho Promise," a 603-carat diamond sold in October 2006 for $12.4 million.

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