Sotheby's, Geneva, May 2007

Lot 174 Colour Change Sapphire and Diamond Ring

Set with an oval colour-change violet sapphire weighing 15.90 carats, the shoulders highlighted with single-cut diamonds, mounted in platinum, size 51.

Accompanied by GRS report no. GRS2006-071192 stating that the sapphire's colour changes from violet in daylight to purple in incandescent light, with no indication of thermal treatment.