A diamond single-stone ring. Photo courtesy Bonhams. 

The cut-cornered step-cut diamond, weighing 11.73 carats, in a four-claw setting, between calibré-cut diamond shoulders, mounted in platinum, UK hallmark, ring size L. Estimate £120,000 - 180,000 (€150,000 - 220,000)

Accompanied by a report from GIA stating that the diamond is J colour, VS2 clarity. Report number 2155537633, dated 3 July 2013.

Bonhams. FINE JEWELLERY INCLUDING SELECTED JEWELS FROM THE COLLECTION OF BARBARA TAYLOR BRADFORD. London, New Bond Street. 5 Dec 2013 - www.bonhams.com