A sapphire and diamond necklace, by Bvlgari. Photo Christie's Image Ltd 2014

Designed as a graduated series of oval-cut sapphires, spaced by marquise-cut diamonds, to the baguette-cut diamond backchain, joined by an oval-cut sapphire clasp, mounted in platinum, 16¼ ins. Signed BVLGARI. Estimate $70,000 – $100,000

Christie's. MAGNIFICENT JEWELS, 16 April 2014, New York, Rockefeller Plaza - www.christies.com