A model poses with the Sun-Drop diamond during a press preview of Sotheby's auction on November 9, 2011 in Geneva. One of the world's largest diamonds, a pear-shaped, 110.3-carat yellow rock, will go up for sale in Geneva on November 15 and is expecting to fetch about 15 million US dollars. The Sun-Drop diamond, discovered in South Africa last year, is billed by Sotheby's as the "world's largest known pear-shaped fancy vivid yellow diamond."