A Sotheby's employee displays the rare Blue Moon Diamond. The 12.03 carat blue diamond is the largest cushion shaped fancy vivid blue diamond to ever appear at auction. Which is estimated to sell between 35-55 million US Dollars, during a preview at the Sotheby's, in Geneva, Switzerland, Wednesday, November 4, 2015. The auction will take place in Geneva, on November 11, 2015. (KEYSTONE/Martial Trezzini)