A plum-sized diamond known as the "Pink Star" was auctioned in Geneva Wednesday for $83 million, a world record for a gemstone. David Bennett, chairman of Sotheby's jewellery division in Europe and the Middle East, brought down the hammer in a Geneva hotel after an intense, five-minute bidding race. The price did not include Sotheby's commission, which the auctioneers were still to reveal. Three years ago, Sotheby's set an auction record of $46.2 million (34 million euros) for a diamond when it sold the "Graff Pink" gemstone.