A single-row pearl necklace with sapphire and diamond clasp, circa 1930. Photo: Bonhams.

The graduating row of 7.1-11.7mm pearls alternating with seed pearls, with a central cushion-shaped sapphire and old brilliant-cut diamond plaque, suspending an 11.7 x 12.7mm pearl drop, sapphire approximately 2.65 carats, diamonds approximately 2.60 carats total, necklace length 46.5cm. Estimate £20,000 - 30,000 (€24,000 - 36,000)

Accompanied by a report from SSEF stating that 32 pearls are natural, saltwater, two pearls are natural, freshwater and three pearls are cultured. Report number 71532, dated 5 November 2013.

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