A shell cameo diadem, circa 1820-30. Photo: Bonhams.

The long central shell panel depicting the three Graces at the centre of a festival of music and dance, flanked by two similarly carved oval cameos, within a beaded surround and decorated to the top with a garland of rose and foliate detail, inner diameter 12.5cm. Estimate £2,000 - 3,000 (€2,400 - 3,600)

Bonhams. JEWELLERY. 12 Feb 2014, London, Knightsbridge - www.bonhams.com