A chalcedony, smoky quartz and cultured pearl bracelet, by René Boivn. Photo Christie's Image Ltd 2014

Designed as a multi-strand chalcedony bead bracelet, joined by a sculpted smoky quartz clasp enhanced with cultured pearls, mounted in 18k white gold, 2005, 6¾ ins. (lenght adjustable), with French assay marks and maker's marks. Signed René Boivin, nos. 1/1, 2005. Estimate $15,000 – $20,000

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