A natural pearl and diamond ring. Photo Bonhams

The 12.5mm natural pearl, between pear-shaped diamond shoulders,diamonds approximately 0.80 carat total, ring size K. Sold for £20,000

An early 20th century natural pearl and diamond pendant necklace. Photo Bonhams

The 9.1mm bouton pearl and cushion-shaped diamond cluster suspending an articulated row of millegrain-set old brilliant-cut diamonds, terminating in a pearl drop with rose and single-cut diamond cap, composite, mounted in silver and gold, old brilliant and cushion-shaped diamonds approximately 1.40 carats total, pendant length 6.5cm, fitted case. Sold for £14,375

A natural pearl and diamond cluster ring, circa 1960. Photo Bonhams

The 9.4mm natural pearl of black tint within a brilliant and baguette-cut diamond surround,diamonds approximately 1.40 carats total, ring size O. Sold for £10,000

Accompanied by a certificate from The Gem & Pearl Laboratory stating that the pearl was found to be natural saltwater with no evidence of treatment. Certificate number 04096, dated 10th May 2011.

A late 19th century diamond and pearl pendant. Photo Bonhams

The old brilliant and single-cut diamond stylised cross set to the centre with an 13.0mm oval natural pearl to an openwork surround highlighted with four 7.0mm pearls and an oval old brilliant and single-cut diamond border and suspensory loop, mounted in silver and gold, later pierced gallery, diamonds approximately 7.65 carats total, length 5.8cm. Sold for £8,750

A diamond and pearl necklace/tiara/brooch combination, circa 1890. Photo Bonhams

The chain of old brilliant and single-cut diamonds, with a large cushion-shaped diamond to the centre, terminating in a similarly cut diamond and drop-shaped pearl tassel of unequal length, suspending either side a graduating fringe of stylised heart-shaped pendants with foliate detail, alternating with dart motifs, set throughout with old brilliant and rose-cut diamonds, mounted in silver and gold,principal diamond approximately 1.30 carats, two diamonds deficient, pearls untested, necklace length 42.0cm, tiara fitting supplied, central diamond and pearl tassel may be converted to a brooch with the supplied diamond bow surmount and pin fitting, fitted tooled leather case by Eredi Levi Leone, Gioiellieri, Asti. Estimate: £15,000 - 20,000, US$ 25,000 - 33,000 - Unsold

A diamond and abalone pearl brooch. Photo Bonhams

Designed as an alpine vista, with abalone baroque pearl mountain and brilliant-cut diamond snow and pine tree detail, diamonds approximately 3.00 carats total, height 4.5cm. Estimate: £4,000 - 6,000, US$ 6,500 - 9,800 - Unsold

Bonhams. Fine Jewellery, 21 Sep 2011 , New Bond Street www.bonhams.com