In this Oct. 4 file photo, a model holds the Archduke Joseph Diamond, a historical diamond, during a Christie's auction preview in Geneva, Switzerland. On Tuesday, Christie's is selling the Archduke Joseph Diamond, one of the rarest and most famous. The 76.02 carat diamond, with perfect color and internally flawless clarity, came from the ancient Golconda mines in India. It is expected to sell for more than $15 million. In 1993, Christie's auctioned it in Geneva where it sold for $ 6.5 million.