London – Bonhams presents its Exceptional Jewels, London sale on 11 June 2026, featuring an outstanding selection of period and antique jewellery from six notable single-owner collections. The auction includes many coveted designs by renowned houses such as Boucheron, Bulgari, Buccellati, Cartier, Carlo Giuliano, Chanel, Tiffany and Van Cleef & Arpels.

Leading the sale is a diamond bandeau tiara from 1924, by Boucheron The openwork bandeau with a central pear-shaped drop, the principal old brilliant-cut diamond, weighing 3.60 carats, is set between scroll, quatrefoil and stylised olive leaves graduating in size towards the centre, set throughout with old brilliant, old single and rose-cut diamonds, accented by collet-set old brilliant-cut diamonds between similarly-set borders. With exceptional provenance, this sale marks the first time the tiara has been seen since its commission from Boucheron in London just over a century ago. It is offered with an estimate of £200,000-300,000.

Jennifer Tonkin, Bonhams Head of Jewellery, UK commented: "Bonhams Exceptional Jewels sale in London features no less than six distinguished and private single-owner collections with many fine examples of antique, 20th century and signed jewels. Of particular note is the diamond bandeau tiara by Boucheron. Inspired by classical antiquity with stylised olive leaf motifs symbolising peace, hope and prosperity, Boucheron in London received the commission shortly before a family wedding in 1924. We're also proud to present a circa 1910 diamond and seed pearl sautoir by Cartier in Paris formerly in the collection of Australia's first international star, Dame Nellie Melba and a rare Art Deco ruby and diamond swag necklace that converts to a bracelet and clip by Sterlé. Among the impressive gems in our upcoming sale is a 5cts Colombian "no oil" emerald ring by Bulgari, a 20cts Fancy Deep Brownish Greenish Yellow diamond ring, a lively 25cts unheated Sri Lankan sapphire ring and a superb 5cts Kashmir sapphire ring of Royal blue colour."

Exceptional Jewels, London also presents a collection of aristocratic jewels from The Sidmouth Family. Henry Addington, 1st Viscount Sidmouth (1757–1844) was a British Tory statesman who served as Speaker of the House of Commons (1798–1801) and Prime Minister (1801–1804). A close ally of William Pitt the Younger, he was active during the era of the French Revolution and the Napoleonic Wars. Collection highlights include:

• The Sidmouth portrait diamond jewel of Emperor Alexander I of Russia, circa 1810. The central portrait miniature is painted in watercolour depicting Alexander I (1777–1825), Emperor of Russia (1801-1825), wearing his uniform and the breast star of the Imperial Russian Order of St. Andrew, beneath a portrait-cut diamond, in a closed-back rose-cut diamond setting, set within a later surround of old brilliant and old cushion-cut diamonds, featuring scroll and foliate motifs. Addington was involved in the arrangements for Alexander I of Russia's visit to England in 1814, and it is likely that the Sidmouth jewel was presented to him as a diplomatic gift on that occasion. Offered with an estimate of £80,000-120,000.

• A diamond floral bracelet, brooch and hair ornament combination, 19th century. Each flowerhead is set with old brilliant, old cushion, old single and rose-cut diamonds, the circa 1860 bracelet strap of flexible linking, mounted in silver and gold. Offered with an estimate of £15,000-20,000.

• A pair of diamond pendent earrings, 19th century. Each articulating openwork drop set throughout with old cushion-shaped diamonds, accented by a central old pear-cut diamond, in pinched-collet settings. Offered with an estimate of £10,000-15,000.

Included in the sale is a Cartier Belle Époque seed pearl and diamond sautoir, circa 1910, originating from the personal collection of the celebrated opera singer, Dame Nellie Melba (1861-1931). Designed with seed pearl linking, accented at intervals by scroll and floral spacers millegrain-set with old brilliant, old single and rose-cut diamonds, suspending a circular pendant, pierced with a radiating floral motif, millegrain-set with similarly-cut diamonds, signed Cartier Paris. The sautoir will be offered with an estimate of £60,000-80,000.

The sale also includes property of a prominent international family, notable lots include:

• A Sterlé Art Deco ruby and diamond necklace. The celebrated French jeweller, rose to prominence for his highly collectible and innovative designs, particularly his early creations from the 1930s and 1940s. The necklace converts to a pair of bracelets and is offered with an estimate of £150,000-250,000.

• A diamond set wheatsheaf brooch, early 19th century. Realistically modelled as four ears of wheat, tied by a ribbon, forming a wheat sheaf, set throughout with pear, cushion and rose-cut diamonds. Offered with an estimate of £25,000-35,000.

• An emerald and diamond brooch, circa 1880. Realistically modelled as ivy leaves, set throughout with old cushion, old brilliant and rose-cut diamonds, issuing three polished emerald beads from rose-cut diamond surmounts. Offered with an estimate of £25,000-35,000.

Another highlight collection includes jewels from the collection of a distinguished European lady:

• An Aldao diamond bracelet and pair of earstuds. The bracelet is set throughout with step-cut diamonds, graduating in size towards the centre, between articulating links set with duos of baguette-cut diamonds. Each earstud is set with a step-cut diamond. Offered with an estimate of £120,000-180,000.

• A diamond ring. The step-cut diamond, of VS1 clarity, weighing 8.54 carats, is set between trilliant-cut diamond shoulders and is offered with an estimate of £85,000-120,000.

• An Aldao sapphire and diamond ring. The oval-cut sapphire, of Burmese origin, weighing 14.65 carats, between demi-lune-cut diamond shoulders, gallery pavé-set with brilliant-cut diamonds, is offered with an estimate of £70,000-100,000.

Other sale highlights include:

• A sapphire and diamond ring. The sugarloaf cabochon sapphire, of Kashmir origin and Royal Blue colour, weighing 5.63 carats, between trilliant-cut diamond shoulders, is offered with an estimate of £80,000-120,000.

• A fancy coloured diamond ring. The cushion-cut natural Fancy Deep Brownish Greenish Yellow diamond, of SI1 clarity, weighing 20.73 carats, is offered with an estimate of £60,000-90,000.

• A sapphire and diamond ring. The cushion-cut sapphire of Sri Lankan origin, with no indications of heating, weighing 25.48 carats, set between pear-shaped diamond shoulders, is offered with an estimate of £60,000-80,000.

• A Bulgari emerald and diamond ring, circa 1960. The octagonal step-cut emerald of Colombian origin, weighing 5.21 carats, between demi-lune-cut diamonds, is offered with an estimate of £50,000-80,000.

• A Cartier diamond and enamel bracelet, circa 1925. The articulated strap set with old brilliant-cut diamonds, central curved plaque set with an old brilliant-cut diamond weighing 5.82 carats, highlighted by an old brilliant-cut diamond to either side, each link with millegrain detailing and black enamel terminals, is offered with an estimate of £60,000-90,000.

• A Chanel diamond 'Fil de Comète' necklace, designed as a shooting comet, set throughout with brilliant-cut diamonds. Gabrielle Chanel launched her first high jewellery collection in 1932, featuring versatile diamond designs. Opposed by the houses of Place Vendôme and the Chambre Syndicale de la Haute Joaillerie, it was withdrawn and dismantled, before being revisited in 2012 by Karl Lagerfeld for Chanel. Offered with an estimate of £60,000-80,000.

(Press Release)