Lot 3. A diamond, copper and gold ring, by Hemmerle. Estimate USD 120,000 - USD 180,000. Price Realised USD 162,500 © Christie's Images Ltd 2016. 

With a bezel-set rectangular-cut diamond, ring size 5 1/2, mounted in copper and 18k rose gold. Signed Hemmerle, with maker's mark

The Collection of Robert and Sylvia Olnick  

Literature: Cf. F. Cailles, René Boivin: Jeweler, Paris, Éditions de l’Amateur, 1994, p. 239

Christie's. Magnificent Jewels, 7 December 2016, New York, Rockefeller Plaza