Black Opal and Diamond Brooch, René Boivin, Circa 1915. Photo Sotheby's

The pentagon-shaped black opal measuring approximately 20.3 by 16.7 mm., the pear-shaped black opal measuring approximately 19.5 by 15.2 mm., old European-cut, single-cut and rose-cut diamonds weighing a total of approximately 2.40 carats, mounted in platinum, maker’s mark, French assay mark, two diamonds missing. With fitted box signed Hunt & Roskell Ltd. Lot sold 46,875 USD

Sotheby's. Magnificent Jewels. New York | 09 Dec 2009 www.sothebys.com