Diamond and onyx  brooch, circa 1915, Cartier, New York. Photo Sotheby's

Suspending on an oscillating pear-shaped diamond weighing 3.46 carats, supported by a link chain set with circular-cut diamonds and marquise-shaped onyx, the diamonds together weighing approximately 1.00 carats, mounted in platinum, signed. Estimate 1,300,000-1,500,000 HKD

NOTE: Accompanied by GIA report numbered 2126058447, dated 26 April 2011, stating that the 3.46 carat diamond is D colour, Internally Flawless clarity; also accompanied by diamond type classification report, stating that the diamond is classified to be a type IIa diamond. Type IIa diamonds are the most chemically pure type of diamond and often have exceptional optical transparency.

 Sotheby's. Magnificent Jewels and Jadeite. Hong Kong | 03 Apr 2012, 02:00 PM www.sothebys.com