Christie's in Geneva has auctioned off the Archduke Joseph Diamond for nearly $21.5m (£13.5m), a world record price per carat for a colourless diamond.
That was well above the expected $15m and more than triple the price paid for it at auction almost two decades ago.
The 76.02-carat diamond, with flawless clarity, came from the ancient Golconda mines in India.
The seller, Alfredo Molina, chairman of California-based jeweller Black, Starr & Frost, said the winning bidder was going to donate the diamond for display at a museum. AP