A model displays a 100.20-carat diamond, left, and a 25.59-carat Burmese ruby during a media preview for the Sotheby's auction in Hong Kong Friday, April 3, 2015. The diamond, a 100.20-carat perfect D color, internally flawless, Type IIa stone in a classic emerald-cut, will be offered in New York Sotheby's auction house on April 21, when it is estimated to sell for US$19-25 million. The 25.59-carat Burmese ruby, cushion-shaped in "pigeon's blood" color, mounted as a ring, will be offered in Geneva Sotheby's auction house on May 12, when it is estimated to sell for US$12-18 million. (AP Photo/Kin Cheung)