76-carat diamond nets a record $21.5M

In this Oct. 4, 2012, photo, a model holds the Archduke Joseph Diamond, a historical diamond, during a Christie's auction preview, in Geneva, Switzerland. On Nov. 13, 2012, Christie's has auctioned off the famed Archduke Joseph Diamond for $21,474,525 including commission, a world auction record price per carat for a colorless diamond.The price was well above the expected $15 million and more than triple the price paid for it at auction almost two decades ago. The 76.02 carat diamond, with perfect color and internally flawless clarity, came from the ancient Golconda mines in India. In 1993, Christie's auctioned it in Geneva where it sold for $6.5 million.

Credit: AP Photo/Keystone/Laurent Gillieron