A color-change sapphire and diamond ring. Photo Christie's Image Ltd 2014

Set with a cushion-cut color-change sapphire, weighing approximately 7.63 carats, within an oval-cut diamond surround, trimmed with single-cut diamonds, to the single-cut diamond gallery and half-hoop, mounted in purple titanium. Estimate $40,000 – $60,000

With report CS 60797 dated 1 May 2014 from the American Gemological Laboratories stating that it is the opinion of the Laboratory that the origin of this color-change sapphire would be classified as Madagascar. No gemological evidence of heat

Christie's. IMPORTANT JEWELS, 10 June 2014, New York, Rockefeller Plaza - http://www.christies.com/