A ruby, emerald and diamond duck brooch, by Cartier. Photo Christie's Image Ltd 2013

Designed as a duck, with carved ruby body, 18k gold and cabochon emerald head to the shield-shaped emerald tail, enhanced with circular-cut diamond detail, mounted in platinum and 18k gold, with French assay marks and maker's marks. Signed Cartier, Paris, no. 09824. Estimate $12,000 – $18,000

Christie's. MAGNIFICENT JEWELS. 10 December 2013. New York, Rockefeller Plaza - www.christies.com