The 910-carat Lesotho Legend was sold in a tender in Antwerp, Gem Diamonds said yesterday. The company found the stone, which is about the size of two golf balls, at its Letseng mine in the country this year.
Although it is the most that Gem has received for a diamond, other diamonds have sold for more.
The Letseng mine is famous for the size of the diamonds it produces and has the highest average selling price in the world. Gem sold a 357-carat stone for $19.3m in 2015, and in 2006 it found the 603-carat Lesotho Promise.