A peridot and diamond 'seahorse' brooch, Jean Schlumberger, Tiffany & Co., French. Photo courtesy Bonhams.

 designed as a seahorse set with circular-cut peridot, accentuated by round brilliant-cut diamonds and a circular-cut ruby eye; signed Tiffany for Tiffany & Co., Schlumberger, made in France, with French maker's mark and assay mark; mounted in eighteen karat gold; length: 3 1/2in. Estimate: US$ 8,000 - 12,000 (€5,900 - 8,900) (£5,000 - 7,500)

Bonhams. Fine Jewelry. October 17th, 2013. New York. www.bonhams.com