A magnificent step-cut diamond, weighing 24.31 carats, D colour and Internally Flawless, is set to go under the hammer at Bonhams London December Jewellery sale next month (5 December 2018). Estimated at £1,300,000 - 1,800,000 (US$1,700,000 - 2,300,000), the diamond hails from a private collection and this is the first time it has come to auction.

Emily Barber, Director of Jewellery at Bonhams UK, said: "This diamond is a magnificent gem, not only due to its significant size – top-quality diamonds over 20 carats are very rare – but also due to its Internal Flawless clarity and its exceptional white colour. It has also been designated as a Type IIa diamond - meaning the diamond is considered chemically pure – and thus possesses exceptional transparency and optical qualities. Interestingly, this is the same classification as The Koh-i-Noor diamond in the British Crown Jewels and the world's largest cut diamond, Cullinan I. It's an extraordinary beauty and we're honoured to be able to offer this to Bonhams' clients this December."  

Sale set to showcase rare Kashmir sapphires
Sapphires from Kashmir have continued to soar throughout this year at Bonhams auctions in London, New York and Hong Kong and this December sale will feature a number of remarkable gems including:

• A SAPPHIRE AND DIAMOND RING. The cushion-shaped sapphire, weighing 8.08 carats, is estimated at £300,000 - 400,000 (US$390,000 - 520,000). Pictured top left.
• A SAPPHIRE AND DIAMOND CLUSTER RING. 
The cushion-shaped sapphire, weighing 9.29 carats, between brilliant-cut diamonds, with tapered baguette-cut diamond shoulders, is estimated at £220,000 - 280,000 (US$280,000 - 360,000). Pictured top middle.
• A LATE 19TH CENTURY SAPPHIRE AND DIAMOND BROOCH. The cushion-shaped sapphire, weighing 4.08 carats, is estimated at £120,000 - 180,000 (US$160,000 - 230,000). It is set within a cushion-shaped diamond surround and scrolling foliate wreath border set with similarly-cut diamonds.
• 26 A SAPPHIRE AND DIAMOND RING BY ASPREY. The cushion-shaped sapphire, weighing 3.09 carats, estimated at £60,000 - 80,000 (US$78,000 - 100,000), is accompanied by a report from SSEF stating that the sapphire is of Kashmir origin and may be called 'royal blue'. Pictured top right.

All four Kashmirs are accompanied by reports confirming no indications of heat treatment.

Emily Barber added: "Considered one of the most coveted gemstones in the world, Kashmir sapphires are in high demand due to their richly saturated velvety blue colour. The four Kashmirs we are auctioning are exceptional gemstones and, given previous Kashmirs' past performance, we anticipate that they will be hotly contested in our December sale."

Staying with sapphires but moving to Sri Lanka, affectionally known as the Island of Gems, Bonhams will also be auctioning A STEP-CUT SAPPHIRE AND DIAMOND RING, weighing 18.32 carats, estimated at £140,000 - 180,000 (US$180,000 - 230,000). The ring is accompanied by two reports confirming the sapphire has no indications of heat treatment.

Fancy coloured diamond ready to dazzle

Bonhams has successfully sold a number of Fancy coloured diamonds this year and, for its last fine jewellery sale of 2018 in London, the auction house will be offering A FANCY COLOURED DIAMOND AND DIAMOND RING 
BY BOODLES. 
The marquise-cut Fancy Intense Blue diamond, weighing 1.03 carats, VS1 clarity, has a pre-sale estimate of £150,000 - 200,000 (US$190,000 - 260,000).

Impressive collection of Van Cleef & Arpels jewellery feature in sale

Jewellery from the house of Van Cleef & Arpels including bracelets, brooches and ear clips will be also offered for sale. The pieces date from the early Art Deco period right through to the 1990s.
Anticipated to be greatly admired during their pre-sale previews in London, New York and Geneva, THREE UNUSUAL GEM-SET BRACELETS estimated at £70,000 - 100,000 (US$90,000 - 130,000) are exceptional examples of the craftsmanship for which Van Cleef & Arpels is renowned for. The trio of bracelets – which can be worn individually or together – are the epitome of style and elegance. Made in 1926 – the early years of the Art Deco period – the bracelets are accompanied by three certificates of authenticity from Van Cleef & Arpels. They come from a private European collection, and this is the first time they will appear at auction.

Each richly coloured bracelet is set with hexagonal-cut gems in a delicate diamond frame, connected by buckle-shaped links of similarly set rose-cut diamonds and horizontal rows of four buff-top calibré-cut gems. The first bracelet is set with peridots and onyx, the second is set with amethysts and the third one is set with citrines.

Emily Barber comments: "The 1920s was a pioneering decade in the history of jewellery, when the top jewellery houses were making some of their finest and most inventive pieces. New advances in cutting techniques gave way to a greater variety of shapes, such as hexagons as seen in these bracelets, and also the 'tallow-cutting' technique which allowed highly skilled jewellers to cut richly coloured gemstones into small buff-top cabochons to build form and texture. These three rare and unusual bracelets perfectly illustrate how Van Cleef & Arpels was innovator par excellence during this period."
Van Cleef & Arpels is also renowned for its unique 'mystery setting' technique which it patented in 1933. This technique gives the allusion that colourful and brilliant gems (like rubies and sapphires) are suspended in an ornate shape, free of any prongs or visible settings. It is still used today and any Van Cleef & Arpels piece that employs the mystery set takes no less than 300 hours to produce. As a result, only a handful of these pieces are produced each year. Bonhams is therefore privileged to offer for sale the following two pieces from Van Cleef & Arpels "Cosmos" collection which features the distinctive quatrefoil flower with heart-shaped petals:
• A PAIR OF 'MYSTERY-SET' SAPPHIRE "COSMOS" EAR CLIPS CIRCA 1991. 
Dated circa 1991, the ear clips are designed as two invisibly-set calibré-cut sapphire flower heads, each with a brilliant-cut diamond pistil, and are estimated at £40,000 - 60,000 (US$52,000 - 78,000).
• A 'MYSTERY-SET' SAPPHIRE "COSMOS" BROOCH. 
Dated circa 1989, the brooch is designed as an invisibly-set calibré-cut sapphire flower blossom with a brilliant-cut diamond pistil on a baguette-cut diamond stem, and is estimated at £40,000 - 60,000 (US$52,000 - 78,000).

Signed jewellery from the world's great jewellery houses to go under the hammer.

An impressive selection of jewellery from the world's most famous jewellery houses and designers features in this sale. Highlights include:
• A RUBY, EMERALD, ENAMEL AND DIAMOND ROSE BROOCH BY LACLOCHE FRÈRES. Dated circa 1925, this brooch is a beautiful example of the early 1920s vogue for pictorial jewels and of Lacloche Frères' execution of design. Estimated at £12,000 - 18,000 (US$16,000 - 23,000), this piece showcases Lacloche Frères' tallow-cutting technique which allowed highly 
skilled jewellers to cut richly coloured gemstones into small buff-top cabochons, these would then be intricately placed to 'paint' a picture across a jewel.
• A GOLD, RUTILATED QUARTZ 'STICKS AND STONES' BANGLE BY ANDREW GRIMA . A real statement piece, the bangle features a large oval polished rutilated quartz, weighing an impressive 328.00 carats, within an engraved gold mount. Dated 1973, the bangle is offered for sale in its original Grima case and is estimated at £12,000 - 18,000 (US$16,000 - 23,000).
• AN EMERALD AND DIAMOND RING BY ANDREW GRIMA, 1971. The large pale green emerald cabochon, within a 'wave' of brilliant-cut diamonds, and an engraved yellow gold mount, is estimated at £30,000 - 40,000 (US$39,000 - 52,000). The lot is accompanied by a letter from Andrew Grima to the owner of this ring stating that the emerald is Siberian, weighing 71.60 carats. Grima describes in the letter how he was given the emerald by a dealer who had acquired "jewellery, stones and objets d'art" that had once belonged to the Czar of Russia.
Both Andrew Grima lots were previously exhibited at London's Goldsmiths' Hall 'Grima Retrospective' in May 1991.
• AN AQUAMARINE AND DIAMOND 'FEUILLE' BROOCH 
BY RENÉ BOIVIN. Dated circa 1950, and featuring a heart-shaped aquamarine enhanced by textured gold leaves and adorned with cushion-shaped diamonds. It is estimated at £15,000 - 20,000 (US$19,000 - 26,000) and the lot is accompanied by a letter of authentication from Françoise Cailles, stating the brooch is by Rene Boivin Joaillier, Paris 1950.
• A GOLD, DIAMOND AND GEM-SET DEMI-PARURE 
BY MELLERIO HERMANOS. This is one of the earliest pieces to be featured in the auction, dated circa 1855, by Mellerio, one of the oldest family jewellers in Europe whose clients included members of Parisian high society as well as European royalty. This suite was exhibited at the Universal Exhibition of 1855 and is estimated at £8,000 - 10,000 (US$10,000 -13,000).