A magnificent diamond single-stone ring, circa 1940. Estimate: £150,000 - 200,000. photo courtesy Bonhams

A magnificent late art deco diamond ring is the highlight of the Bonhams Fine Jewellery sale which will take place in New Bond Street on September 22nd. The Asscher-cut diamond, weighing 6.82 carats, is D colour, potentially flawless and Type IIa. Type IIa diamonds are the most chemically pure type of diamond and possess exceptional optical transparency. Famous gem diamonds that are Type IIa include the Cullinan I and the Koh-i-noor. This ring, estimated at £150,000-200,000, has never before been seen at auction and its colour, clarity and shape are exquisite. Accompanied by a GIA certificate stating that the diamond is D colour, VVS2 clarity, potentially flawless. Certificate number 110202035801, dated 14 June 2010, also accompanied by a GIA certificate stating that the diamond is type IIA. Certificate number 2125219268, dated 10 June 2010.

The sale also features two other impressive gem-quality diamond rings: a brilliant-cut diamond, weighing 3.00 carats, D colour, Internally Flawless, estimated at £70,000 – 90,000

A diamond single-stone ring. Estimate £70,000 – 90,000. photo courtesy Bonhams

The brilliant-cut diamond, weighing 3.00 carats, within a four-claw setting, to a plain hoop, ring size M. Accompanied by a GIA certificate stating that the diamond is D colour, Internally Flawless clarity. Certificate number 13374015, dated 14th July 2010.

and a pear-shaped diamond, weighing 5.00 carats, D colour, VS2 clarity, estimated at £80,000 – 100,000.

A diamond single-stone ring. Estimate 80,000 – 100,000. photo courtesy Bonhams

The claw-set pear-shaped diamond, weighing 5.00 carats, to a plain hoop, ring size D. Accompanied by a copy of a GIA certificate stating that the diamond is D colour, VS2 clarity. Certificate number 8342229, dated 5th April 1993.

Bonhams is also delighted to present a superb selection of antique 19th century jewellery, which is seen increasingly infrequently on the market. A late 19th century sapphire and diamond necklace, estimated at £45,000 - 55,000.

A late 19th century sapphire and diamond necklace. Estimate £45,000 - 55,000. photo courtesy Bonhams

Designed as a chain of graduating old brilliant-cut diamond and cushion-shaped sapphire clusters, connected by collet-set old brilliant-cut diamond links, mounted in silver and gold, diamonds approximately 30.00 carats total, sapphires approximately 42.75 carats total, length 40.7cm., fitted velvet case

And an early 19th century diamond necklace with circular clusters of cushion-shaped diamonds, estimated at £25,000 – 30,000, are both outstanding examples of their type.

A diamond necklace, circa 1820. Estimate £25,000 – 30,000. photo courtesy Bonhams

The articulated collar composed of alternating circular clusters and openwork spindle-shaped links, collet-set throughout with cushion-shaped diamonds, graduating in size from the centre, mounted in silver and gold, some in closed-back settings, diamonds approximately 32.00 carats total, length 38.5cm., central clusters detach to form a bracelet, bracelet length 16.6cm., cased by S J Phillips

A pair of diamond pendeloque earrings, circa 1810. Estimate: £12,000 - 15,000. photo courtesy Bonhams

Each cushion-shaped diamond cluster surmount suspending a diamond-set ribbon bow motif, terminating in a cushion-shaped diamond pendant, within a drop-shaped border of smaller cushion-shaped diamonds, mounted in silver and gold, the smaller diamonds in closed-back settings, diamonds approximately 8.90 carats total, later screw fittings, cased by S J Phillips

A further highlight is an early 20th century emerald and diamond choker/ bracelet combination. This fantastic piece is estimated at £10,000 – 15,000.

An early 20th century emerald and diamond choker/bracelet combination, circa 1910. Estimate £10,000 – 15,000. photo courtesy Bonhams

Designed as a highly articulated series of panels, some with pierced detail, pavé-set throughout with old brilliant and single-cut diamonds and highlighted at intervals with rectangular step and calibré-cut emeralds, the gallery with delicate foliate engraving, one calibré-cut emerald deficient, choker separates to form a pair of bracelets, length of each bracelet 16.8cm. (2)

A rare catalogue of Henry Philip Hope's collection of pearls and precious stones will also be offered in this sale. Published in 1839, this volume sets out his celebrated collection in its entirety, including the famous Hope Pearl and the infamous Hope Diamond, the extraordinary blue diamond of 45.52 carats, once believed to be cursed, which had been part of the French crown jewels and is now in the Smithsonian Institution in Washington. The book, which belonged to the Hope family and has since passed by descent to the vendor, is estimated at £2,000-3,000.

Henry Philip Hope, of the renowned Anglo-Dutch banking family, was a patron of the arts and a great connoisseur of gems and jewellery. His celebrated collection included the famous Hope Pearl, a very large natural saltwater pearl, and the infamous Hope Diamond, the rare blue diamond of 45.52 carats, believed to be cursed, which had been part of the French crown jewels and is now in the Smithsonian Institution. After his death in 1839 his collection was eventually divided between his three nephews. Items of furniture and works of art belonging to the Hope family will be sold by Bonhams on 3 November 2010.
Henry Philip Hope, of the renowned Anglo-Dutch banking family, was a patron of the arts and a great connoisseur of gems and jewellery. His celebrated collection included the famous Hope Pearl, a very large natural saltwater pearl, and the infamous Hope Diamond, the rare blue diamond of 45.52 carats, believed to be cursed, which had been part of the French crown jewels and is now in the Smithsonian Institution. After his death in 1839 his collection was eventually divided between his three nephews. Items of furniture and works of art belonging to the Hope family will be sold by Bonhams on 3 November 2010.

Hope, Henry Philip, A Catalogue of the Collection of Pearls and Precious Stones. Estimate £2,000-3,000. photo courtesy Bonhams

Jean Ghika, Director of the Jewellery Department comments, "we are delighted to be chosen to handle the sale of such an exceptional selection of diamonds and antique and period jewels and anticipate they will be strongly competed for on the day of the sale".