An amethyst, diamond and cultured pearl brooch. photo courtesy Bonhams

The large cushion-shaped amethyst within a 19th century openwork frame of old brilliant and rose-cut diamonds, suspending a detachable cultured pearl drop with rose-cut diamond cap, diamonds approximately 6.50 carats total, width 5.2cm. Estimate: £10,000 - 15,000

A 19th century amethyst necklace and a pair of amethyst and diamond earrings. photo courtesy Bonhams

The necklace composed of graduating oval-cut foiled amethyst links, suspending a fringe of pear-shaped foiled amethyst drops, with an oval-cut and pear-shaped foiled amethyst pendant to the centre, the associated pair of earrings each set with a single foiled oval-cut amethyst, suspending three old brilliant-cut diamond drops, all stones in closed-backed pinched collet settings, necklace length 38.0cm., earring length 2.4cm. (2) v- Estimate: £4,500 - 5,500

Bonhams. Fine Jewellery, 22 Sep 2010, New Bond Street www.bonhams.com