A sapphire and chalcedony "quatre corps" ring, by René Boivin. Photo Christie's Image Ltd 2014

Designed as four alternating rows of circular and oval-cut sapphires and chalcedony, mounted in blackened 18k gold, 2005, with French assay mark and maker's mark. Signed René Boivin, nos. 1/1, 2005. Estimate $4,000 – $6,000

Christie's. MAGNIFICENT JEWELS, 16 April 2014, New York, Rockefeller Plaza -www.christies.com