An art deco emerald, diamond and rock crystal "Roof" ring, by Suzanne Belperron. Photo Christie's Image Ltd 2014

Designed as a carved rock crystal ring of bombé design, centering upon a bezel-set cabochon emerald, flanked on either side by a bezel-set pear-shaped diamond, mounted in platinum and gold, circa 1935, ring size 6¼. Estimate $70,000 – $100,000

With certificate of authenticity from Belperron

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