A sapphire single-stone ring, circa 1950. Photo: Bonhams.

The large step-cut sapphire, weighing 23.24 carats, between shoulders set with baguette and brilliant-cut diamonds, ring size O½, cased by Collingwood of Conduit St, 46 Conduit St, W1. Estimate £18,000 - 25,000 (€22,000 - 30,000)

Accompanied by a report from the Gem & Pearl Laboratory stating that the sapphire is of Sri Lankan origin, with no evidence of heat treatment. Report number 09590, dated 18 March 2014.

Bonhams. FINE JEWELLERY, 30 Apr 2014, London, New Bond Street - www.bonhams.com