The most important set of Chameleon diamonds ever to be presented at auction leads the forthcoming Rare Jewels and Jadeite sale at Bonhams Hong Kong on November 25.

The exquisite diamond necklace features nine Chameleon diamonds weighing 13.87 carats total and is expected to fetch between HK$1,600,000 and HK$3,000,000.

“Chameleon diamonds are amongst the rarest and most mysterious of coloured diamonds. Depending on temperature and light conditions, the diamond’s colour transforms from “olive” green to a mesmerising brownish yellow or yellow,” explains Bonhams Asia Director of Jewellery, Graeme Thompson.

“Due to their rarity, little gemmological information exists on Chameleon diamonds and scientists have yet to confirm the mechanism that causes their colour-changing behaviour. We are excited to present this extremely rare phenomenon in our upcoming sale.”

Alongside this piece, the Hong Kong sale features an exceptional range of best-in-class diamonds, coloured gemstones, and signed jewellery. There are more than 150 lots with estimates ranging from HK$30,000 for a cultured pearl and diamond necklace, to HK$7,500,000 for the finest jade bangle to be offered at auction this year.

Coloured Diamonds

In addition to the Chameleon diamonds, Bonhams presents a kaleidoscopic selection of rare coloured diamonds including an Intense Blue, three green diamonds, a 7 carat faint pink, and a striking collection of Vivid Yellows.

Highlight pieces include:

• A 1.45 carat Natural Fancy Intense Blue diamond ring estimated at HK$2,000,000 to HK$3,000,000

• A 5.64 carat Natural Fancy Vivid Yellow Internally Flawless emerald cut diamond ring by Cartier estimated at HK$3,000,000 to HK$4,000,000

• A 3.15 carat Natural Fancy Intense Yellowish Green diamond ring estimated at HK$1,300,000 to HK$1,800,000

• A 1.51 carat Natural Fancy Intense Pinkish Purple diamond ring estimated at HK$2,000,000 to HK$3,000,000

• A 1.24 carat Natural Fancy Intense Green diamond ring estimated at HK$800,000 to HK$1,200,000

“Natural coloured diamonds can be found in almost every tone of the rainbow and can come in over 230 colour combinations. They are formed when certain elements are captured within the diamond structure as it is forming from carbon atoms and this process can produce the breathtaking and rare colours we see.” Thompson adds.

Jadeite

The sale headlines its jadeite selection with an exceptional jade bangle. Expected to fetch between HK$7,500,000 and HK$10,000,000, it is highly translucent with an intense to bright emerald green colour throughout.

“This bangle is the finest example to come to market this year that we know of, with its divinely rich colour and incredible translucency. We are delighted to be able to offer it,” said Thompson.

Coloured Gemstones

The sale features an extensive but carefully curated selection of coloured gemstones including Kashmir sapphires, Colombian emeralds, Burmese rubies, sapphires, spinels, Brazilian Paraiba Tourmaline and Sri Lankan. Padparadschas.

Highlights include:

• Kashmir Sapphire: Four significant Kashmir sapphire and diamond rings – 1.82 carats (HK$130,000 to HK$200,000), 2.55 carats (HK$300,000 to HK$400,000), 5.02 carats (HK$2,500,000 to HK$3,500,000) and 6.71 carats (HK$2,500,000-3,500,000)

• Colombian Emerald: A 4.35 carat Colombia no-oil emerald and diamond ring estimated at HK$750,000-1,500,000; and a pair of Colombian no-oil earrings at 3.91 and 4.49 carat for HK$1,300,000-2,300,000

• Burmese Ruby: A 4.02 carat Burma no heat ‘Pigeon’s Blood’ ruby and diamond ring for HK$4,800,000-6,800,000

• Brazilian Paraiba Tourmaline: A 6.40 carat natural unheated Paraiba tourmaline from Brazil, set as a ring estimated at HK$1,750,000-HK$3,000,000

• Burmese Spinel: A collection of 32 Natural Burmese unheated spinels from Mogok set in mother-of-pearl l as an impressive necklace, bracelet, earring and ring suite for HK$1,500,000-2,000,000.

Signed Jewellery

Reflecting the ever-growing market interest in signed jewellery, Bonhams features an exquisite range of signed jewellery in this sale with a selection from the important Houses including Bulgari, Cartier, Chaumet, Graff, Harry Winston and Van Cleef & Arpels as well as from contemporary designers such as Alexander Laut.

Highlights include:

• Bulgari: An exceptional necklace and earring suite by Bulgari (estimated at HK$4,700,000-6,000,000)

• Cartier: A Natural Fancy Vivid Yellow internally flawless diamond ring weighing 5.64 carats (estimated at HK$3,000,000-4,000,000); and an exceptional Diamond and Coloured Diamond pendant necklace with a 5.93 D IF Type IIa pear-shape and 2.55 carat Natural Fancy Vivid Orange Yellow pear-shape diamond (estimated at HK$3,500,000-5,500,000)

• Van Cleef & Arpels: A Jadeite ‘Alhambra’ necklace (estimated at HK$150,000-200,000); A Ruby and Diamond bracelet circa 1965 (estimated at HK$280,000-380,000)

• Harry Winston: A 5.04 carat D IF Type IIa pear-shape diamond ring circa 1955 estimated at HK$2,000,000-3,000,000

The sale also highlights a range of motif brooches including:

• A diamond, ruby, emerald, sapphire and Lapis Lazuli kingfisher brooch by Cartier (estimated at HK$180,000-280,000);

• From Chaumet: a ruby, sapphire, turquoise and diamond exotic bird brooch (HK$80,000-120,000); and a diamond and coloured diamond flower brooch (estimated at HK$100,000-200,000)

• A pair of winking cat ruby, diamond and turquoise novelty brooches (estimated at HK$40,000 to HK$60,000)

• An early 20th century emerald diamond and pearl brooch/pendant, circa 1900 (estimated at HK$65,000-85,000)

• A Lapis Lazuli and diamond butterfly brooch by Van Cleef & Arpels (estimated at HK$75,000-100,000)

• A sapphire and diamond brooch by Alexander Laut (estimated at HK$95,000-120,000)