Platinum, Treated Cognac Diamond and Diamond Ring-Dant. Photo: Courtesy Doyle New York 

One pear-shaped treated cognac diamond ap. 2.90 cts., 55 diamonds ap. 3.25 cts., signed Ring-Dant, ap. 10.7 dwt. Size 7 1/2.  This diamond has been weighed. Treated cognac diamond: deep bright brownish-orange with yellow bow tie in center, VS. This diamond has not been tested. Brilliant. Diamonds: I-J-VS, baguettes very lively. Good condition. Detachable from shank, can be worn as pendant. 1 1/4 x 7/8". Estimate $4,000-6,000

Doyle New York. Important Estate Jewelry - Wednesday, September 21, 2011 at 10am. www.doylenewyork.com