A late 19th century diamond fringe necklace. Photo Bonhams

The graduated chain of collet-set old brilliant-cut diamonds, each suspending a rose, single and old brilliant-cut diamond foliate drop with an old brilliant-cut diamond finial, highlighted with rose-cut diamond spacers and clasp, mounted in silver and gold,old brilliant and single-cut diamonds approximately 33.90 carats total, length 37.0cm - Estimate: £25,000 - 30,000, US$ 41,000 - 49,000

A late 19th century gold and diamond necklace. Photo Bonhams

The finely modelled garland of gold leaves highlighted by old brilliant-cut diamond buds, on an articulated knife-wire backchain with cushion-shaped diamond and foliate detail,diamonds approximately 11.00 carats total, French maker's mark, probably for Pierre-Isadore Sauvage, French assay marks, length 38.0cm, cased by Véronique Bamps, 28 Boulevard de Waterloo, Bruxelles - Estimate: £15,000 - 20,000, US$ 25,000 - 33,000

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

A pair of diamond pendent earrings, last quarter of the 19th century. Photo Bonhams

Each foliate surmount suspending a collet-set cushion-shaped diamond and a further pear-shaped diamond central drop, within an openwork scrolling surround, set throughout with old brilliant-cut and cushion-shaped diamonds, mounted in silver and gold, diamonds approximately 9.20 carats total, later screw fittings, length 5.5cm - Estimate: £10,000 - 15,000, US$ 16,000 - 25,000

A 19th century diamond spray brooch, circa 1880. Photo Bonhams

Designed as a flower in bloom, the leaves, stem, bud and petals set throughout with cushion-shaped, old brilliant, single and rose-cut diamonds, mounted in silver and gold, both the flowerhead and the lower section detachable to form two separate brooches, fittings now deficient,diamonds approximately 18.00 carats total, French maker's mark, French assay mark, one diamond deficient, length 12.5cm - Estimate: £8,000 - 10,000, US$ 13,000 - 16,000

A diamond brooch, circa 1840. Photo Bonhams

The pierced lozenge-shaped plaque of stylised foliate design, set to the centre with a collet-set cushion-shaped diamond, weighing 3.44 carats, within a surround of single, old brilliant and rose-cut diamonds, mounted in silver and gold,remaining diamonds approximately 2.10 carats total, later pin fitting, length 3.5cm, cased by S.J Philips - Estimate: £4,000 - 6,000, US$ 6,500 - 9,800

A diamond cluster ring, circa 1820. Photo Bonhams

The oval rose-cut diamond surrounded by a single-cut diamond border, within foiled closed-back settings, to fleur-de-lys shoulders and a reeded hoop, mounted in silver and gold,ring size O - Estimate: £4,000 - 6,000, US$ 6,500 - 9,800

A pair of diamond brooch/pendants, circa 1870. Photo Bonhams

Each scrolling surmount suspending a graduated foliate fan with a raised central cluster, set throughout with rose, single and old-brilliant-cut diamonds,diamonds approximately 4.30 carats total, detachable brooch fittings, later rhodium plated, length 4.7cm - Estimate: £3,500 - 4,500, US$ 5,700 - 7,400

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