A woman displays a 100.20-carat diamond ring in front of Roy Lichtenstein's 1962 painting "The Ring (Engagement)" at a pre-auction viewing at Sotheby's in Los Angeles, California March 25, 2015. Sotheby's says the ring is expected to sell for US $19-25 million, and the painting of the ring for around US $50 million. REUTERS/Lucy Nicholson