An emerald and diamond necklace, by Van Cleef & Arpels. Estimate $150,000 – $200,000. Photo Christie's Image Ltd 2015

Designed as a series of graduated circular-cut diamond plaques, set at the front with rectangular-cut emeralds, spaced by baguette-cut diamonds, 15 ins., mounted in gold, in a Van Cleef & Arpels brown suede envelope case. Signed V.C.A. for Van Cleef & Arpels, N.Y., no. 54640

Christie's. IMPORTANT JEWELS, 20 October 2015, New York, Rockefeller Plaza