A model displays both a 100.20 carats (top) and a 25.59 carats, that is known as 'The Sunrise Ruby', diamond rings at a pre-auction viewing at Sotheby's in Hong Kong April 3,2015. According to a press release by Sotheby's, the 100.20 carats diamond, described as "internally flawless" by Sotheby's, is expected to fetch between $19-25 million in a New York auction on April 21, 2015. The Burmese cushion-shaped ruby diamond 'The Sunrise Ruby', mounted by Cartier as a ring, is expected to fetch between $12-18 million in Geneva on May 12, 2015. REUTERS/Tyrone Siu