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Lot 665. A rare 12.92 carat Kashmir Sapphire and Diamond Ring, Circa 1980. Estimate HK$ 950,000 - 4,000,000 (€ 100,000 - 440,000). © Bonhams 2001-2018

Hong Kong – The recent discovery of a 12.92 carat Kashmir sapphire in a client's bank vault could prove to be an exciting windfall for one lucky family who has no idea of the gemstone's value. Estimated to fetch between HK$950,000 and HK$4,000,000 (US$120,000 – 510,000), the unheated Kashmir sapphire and diamond ring leads Bonhams upcoming Rare Jewels and Jadeite sale in Hong Kong on 27 May.

Bonhams Asia Director of Jewellery, Graeme Thompson, assessed the sapphire and believed it to be of Kashmir origin. The gemstone was then sent by Bonhams to Switzerland for scientific testing where it was confirmed as an extremely rare Kashmir sapphire, which had previously been assessed by other auction houses at HK$30,000-50,000 (US$3,800-6,300).

"Kashmir sapphires are the rarest of gemstones and collectors are prepared to pay princely sums for top-quality specimens, which have experienced a 970 per cent price increase for sapphires[1] over the past decade," commented Graeme Thompson. "We are delighted to headline this extremely rare piece in our upcoming sale. Sapphires were first discovered in Kashmir around 1880 but most Kashmir mines rapidly depleted soon after. Termed as 'blue velvet' due to the superiority of their superb cornflower blue hue, most Kashmir sapphires that appear on the market today were discovered more than 100 years ago."

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Lot 665. A rare 12.92 carat Kashmir Sapphire and Diamond Ring, Circa 1980. Estimate HK$ 950,000 - 4,000,000 (€ 100,000 - 440,000). © Bonhams 2001-2018

The cushion-shaped sapphire, weighing 12.92 carats, within a marquise, baguette and brilliant-cut diamond surround, diamonds approximately 3.50 carats total, maker's mark, ring size 8

Accompanied by a SSEF report stating that the natural sapphire has no indications of heat treatment and originates from Kashmir. Report number 98761, dated 15 March 2018. 

Accompanied by a Gubelin report stating that the natural sapphire has no indications of heat treatment and originates from Kashmir. Report number 18030099, dated 21 March 2018. 

Also accompanied by a Gubelin information sheet stating that gem quality Kashmir sapphires are rare.

Alongside this piece, the Hong Kong sale features an exceptional range of rubies, emeralds, spinels, diamonds and a collection of signed jewellery from the most famous Houses including Van Cleef and Arpels, Cartier, Harry Winston, Graff, Chopard and Bulgari across some 168 lots valued from HK$20,000 to HK$5,000,000.

Emeralds and Rubies

Bonhams presents best in class Burmese 'Pigeon's Blood' Ruby and Diamond ring (estimate at HK$3,500,000-5,000,000/US$445,000-635,000) and an 8.88 carat Colombia 'No Oil' Emerald and Diamond ring (estimate at HK$5,000,000-6,000,000/US$635,000-765,000) from a private Asian collector who purchased the pieces in a Hong Kong auction in May 2016 and is now looking to sell both rings to capitalise on price increases since, and to reinvest in higher value items.

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Lot 660. A Fine 4.01 carats Burmese 'Pigeon's Blood' Ruby and Diamond Ring. Estimate HK$ 3,500,000 - 5,000,000 (€ 380,000 - 550,000). © Bonhams 2001-2018

The cushion-shaped ruby, weighing 4.01 carats, between similarly cut diamond shoulders, accented by brilliant-cut diamonds, diamonds approximately 2.60 carats total, ring size 5¾

Accompanied by a SSEF report stating that the natural ruby is 'Pigeon's Blood' red colour, has no indications of clarity enhancement and originates from Burma (Myanmar). Report number 78688, dated 11 March 2015. 

Accompanied by a Gubelin report stating that the natural ruby is 'Pigeon's Blood' red colour, has no indications of clarity enhancement and originates from Burma (Myanmar). Report number 13116110, dated 23 November 2013. 

Accompanied by a GRS report stating that the natural ruby is vivid red colour (GRS type 'pigeon's blood red'), has no indications of thermal treatment and originates from Burma (Mogok, Myanmar). Report number GRS2014-020337, dated 25 February 2014.  

Provenance: Previously purchased at Christie's Hong Kong, Magnificent Jewels auction on 31 May 2016, sale number 12573, Lot 2029, by an Asian private collector.

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Lot 659. 8.88 carat Colombia 'No Oil' Emerald and Diamond ring. Estimate HK$ 5,000,000 - 6,000,000 (€ 550,000 - 660,000). © Bonhams 2001-2018

The step-cut emerald, weighing 8.56 carats, between triangular-cut diamond shoulders, diamonds approximately 1.20 carats total, ring size 5½

Accompanied by a SSEF report stating that the natural emerald has no indications of clarity enhancement and originates from Colombia. Report number 98168, dated 7 March 2018. 

Provenance: Previously purchased at Christie's Hong Kong, Magnificent Jewels auction on 31 May 2016, sale number 12573, Lot 1841, by an Asian private collector. 

"The market has experienced the biggest price increases for emeralds and rubies which respectively have seen a 1,900 per cent price increase for emeralds[2] and a 1,100 per cent increase for rubies[3] in the past 10 years", said Graeme Thompson.

Spinels

According to Bonhams, there has been a noticeable interest in spinel with many collectors recognising their value and wanting to buy the best examples, with pieces over 10 carats considered incredibly rare. The international auction house still maintains the world record for the sale of exceptional 19th century large octagonal step-cut 50.13 carats spinel and diamond jewel for £962,500 in April 2015.

For its upcoming sale in Hong Kong, Bonhams features a 36.68 carats pear-shaped spinel and diamond necklace, estimated at HK$3,000,000-5,000,000 (USD$380,000-630,000).

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Lot 631. An Exceptional 36.68 carats Burmese Pear-shaped Spinel and Diamond Necklace. Estimate HK$ 3,000,000 - 5,000,000 (€ 330,000 - 550,000). © Bonhams 2001-2018

The elongated pear-shaped spinel, weighing 36.68 carats, within a pear, marquise and brilliant-cut diamond undulating, openwork surround, suspended from a pear and brilliant-cut diamond surmount, completed by a brilliant-cut diamond rivère necklace, diamonds approximately 12.05 carats total, necklace detachable, lengths: pendant 6.0cm, necklace 40.6cm

Accompanied by a SSEF report stating that the natural spinel has no indications of heat treatment and originates from Burma (Myanmar). Report number 98381, dated 7 March 2018. 

Also accompanied by a premium appendix from SSEF stating that the spinel exhibits a remarkable size for its attractive and vivid red colour and excellent purity.

Accompanied by four GIA reports stating that the 0.90 to 0.42 carat pear-shaped diamonds are D colour and IF to VVS2 clarity. Report numbers 5146401749, 1209972636, 1189824223, 1208546257.

Note: Found in various locations among which is the famed Mogok mine in Mynamar (Burma). Alongside Mogok's more famous ruby yields, spinels come in numerous colours and hues from colourless to black. Red spinels are among the most prized due in no small part to their close resemblance to rubies. 

For centuries, spinels were confused with and indeed called rubies: the 170ct "Black Prince Ruby" and the 352ct "Timur Ruby" - both in the British Crown Jewels and both from Tajikistan – are in fact spinels.  

In modern times, spinels have enjoyed increased attention from collectors and designers alike who appreciate this striking and rare gemstone particularly in its untreated form.

Signed Jewellery

Signed jewellery has achieved remarkable prices over the past few years at auction, with buyers from around the world seeking out the best examples made by the great Houses including Van Cleef and Arpels, Cartier, Harry Winston, Graff, Chopard, Bulgari and Tiffany & Co.

"Signed jewellery offered at auction is undoubtedly the best value in terms of quality, style and affordability. Very often these rare jewels are one of a kind and will never be produced again," comments Graeme Thompson.

Bonhams showcases for its sale a number of signed jewellery pieces including:

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Lot 617. An Emerald and Diamond necklace set in platinum, by Bulgari, circa 1960. Estimate HK$ 2,500,000 - 3,500,000 (€ 270,000 - 380,000). © Bonhams 2001-2018

The articulated necklace set with a double row of marquise and brilliant-cut diamonds, suspending fifty drop-shaped emeralds, graduating in size towards the front, diamonds approximately 45.00 carats total, emeralds approximately 78.00 carats total, signed Bulgari, French assay marks, inner circumference 37.0cm.

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Lot 616. An impressive 27.91 carats Colombian Emerald and Diamond Ring, by Harry Winston. Estimate HK$ 1,600,000 - 2,200,000 (€ 170,000 - 240,000)© Bonhams 2001-2018

The step-cut emerald, weighing 27.91 carats, between triangular-cut diamond shoulders,maker's mark, French assay marks, diamonds approximately 3.80 carats total, ring size 6½ with sizer.

Accompanied by a SSEF report stating that the emerald has minor indications of 'oil type' clarity enhancement and originates from Colombia. Report number 87498, dated 1 September 2016.

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Lot 578. An Art Deco Diamond and Emerald Bracelet, by Cartier. Estimate HK$ 310,000 - 500,000 (€ 34,000 - 55,000)© Bonhams 2001-2018

The openwork bracelet set with five step-cut emeralds and old brilliant-cut diamonds, each plaque connected by french-cut diamonds, diamonds approximately 16.80 carats total, emeralds approximately 1.80 carats total, signed Cartier, numbered, length 18.5cm.

 

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Lot 640. A Fine 70.00 carats Tanzanite, Sapphire, Paraiba Tourmaline, and Diamond Dress Ring, by Chopard. Estimate HK$ 380,000 - 580,000 (€ 41,000 - 63,000)© Bonhams 2001-2018

Modelled as nine penguins gathering around a pool of water, centrally set with an oval-cut tanzanite, the penguins pavé-set with circular-cut sapphires and brilliant-cut diamonds, to a similarly set diamond gallery and hoop, accented by circular-cut paraiba tourmalines, signed Chopard, numbered, diamonds approximately 4.10 carats total, tanzanite approximately 70.00 carats, sapphires approximately 6.30 carats total, ring size 6¼.

Note: Founded in Switzerland in 1860 by Louis-Ulysse Chopard, the house has steadily grown under the two family owners it has enjoyed since inception: first the Chopards and since 1963 the Scheufele family. From its initial role as a ladies' and pocket watch maker based in rural Switzerland, the house is now an internationally-present and globally-recognised watch and jewellery heavyweight, aided by signature designs such as the floating so-called "Happy Diamonds" and red carpet association through the sponsorship of the Cannes Film Festival. 

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Lot 572. A Pair of Diamond, Ruby and Sapphire 'Danseuse' Brooches, by Van Cleef and Arpels, Circa 1950. Estimate HK$ 280,000 - 580,000 (€ 31,000 - 63,000)© Bonhams 2001-2018

Each designed as a ballerina with a rose-cut diamond head, the tutu accented by circular-cut rubies or sapphires, each signed Van Cleef & Arpels, numbered, maker's marks, French assay marks, each length 2.6cm (2).

Jadeite

The following lots headline the jadeite section of the Hong Kong sale, including:

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Lot 562. A pair of highly translucent jadeite saddle rings. Estimate HK$ 100,000 - 200,000 (€ 11,000 - 22,000)© Bonhams 2001-2018

The pair of highly translucent jadeite saddle rings of bright emerald green colour, measuring approximately 24.4 x 15.4 x 23.6 x 7.3mm and 24.4 x 15.4 x 23.7 x 7.5mm, accompanied by earring surmounts, ring sizes 4½.

Accompanied by two Hong Kong Jade & Stone Laboratory reports stating that the natural colour fei cui (jadeite jade) have no resin detected. Report numbers KJ 97743 and KJ 97742, both dated 2 March 2018.

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Lot 622. A highly translucent jadeite bangle. Estimate HK$ 680,000 - 950,000 (€ 74,000 - 100,000)© Bonhams 2001-2018

The highly translucent jadeite bangle of light green body colour, with a section of bright emerald green patch, the outer, inner diameter and thickness 80.3 x 57.2 x 12.0mm.

Accompanied by a Hong Kong Jade & Stone Laboratory report stating that the natural colour fei cui (jadeite jade) has no resin detected. Report number KJ 98000, dated 4 April 2018.

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Lot 595. A highly translucent jadeite cabochon of intense emerald green colour and diamond ringEstimate HK$ 480,000 - 560,000 (€ 52,000 - 61,000)© Bonhams 2001-2018

The highly translucent jadeite cabochon of intense emerald green colour, within a marquise-cut diamond surround, diamonds approximately 3.20 carats total, jadeite measuring approximately 12.7 x 11.8 x 7.8mm, ring size 6¾.

Accompanied by a Hong Kong Jade & Stone Laboratory report stating that the natural colour fei cui (jadeite jade) has no resin detected. Report number SJ 166687, dated 4 April 2018.

Colourless and Fancy Coloured Diamonds:

The sale features an extensive array of colourless and fancy coloured diamonds including:  

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Lot 658. An exceptional 6.03 carats D flawless Type IIA emerald cut diamond ring. Estimate HK$ 1,600,000 - 3,000,000 (€ 170,000 - 330,000)© Bonhams 2001-2018

The step-cut diamond, weighing 6.03 carats, between baguette-cut diamond shoulders, to a similarly cut diamond gallery, signed, ring size 4¾.

Accompanied by a GIA report stating that the diamond is D colour and Flawless clarity, with Excellent Polish and Symmetry. Report number 2171773330, dated 14 March 2018. 

Also accompanied by an appendix from GIA stating that the diamond is Type IIa and therefore chemically pure, dated 13 March 2018. 

Note: A D Flawless diamond is a true rarity in what is already a rarefied world. With fewer than 20% of all diamonds mined worldwide being of high enough quality to be used in jewellery, only a select few of these are of the whitest D colour and of these, even fewer have no internal or external inclusions, flaws or blemishes which allow them to be classified as Flawless. 

Diamonds are classified into two groups based on the relative presence or absence of nitrogen. Type I diamonds contain nitrogen while Type II diamonds contain little if any nitrogen and are considered to be chemically pure. Type IIa diamonds make up less than 2% of all natural diamonds and show exceptional transparency. 

Type IIa diamonds were first identified as originating from India – specifically from the fabled Golconda region – but have since been found across the world. Many famous diamonds such as the Cullinan and the Koh-i-Noor are Type IIa diamonds. 

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Lot 655. 'The Bordeaux Red'. A rare cushion-shaped fancy brownish red 1.30 carats diamond and diamond ringEstimate HK$ 1,600,000 - 3,000,000 (€ 170,000 - 330,000)© Bonhams 2001-2018

The cushion-shaped fancy brownish red diamond, weighing 1.30 carats, between similarly cut diamond shoulders, ring size 5½

Accompanied by a GIA report stating that the 1.30 carat diamond is Natural Fancy Brownish Red colour. Report number 2165505734, dated 5 August 2015. 

Accompanied by a GIA monograph entitled 'The Bordeaux Red'.

Note: Red is the rarest of all coloured diamonds and like pink diamonds, they are created through a process known scientifically as "Plastic Deformation". Such is their rarity that GIA (Gemological Institute of America) records show that from 1957 to 1987, not one laboratory report was issued for a diamond with "red" as the only descriptive term. Today, only a handful of red diamonds are recovered every few years, with the majority weighing considerably less than 1 carat. The largest red diamond graded by the GIA is the Moussaieff Red which weighs 5.11ct and which came from Brazil. While all other coloured diamonds come in several intensity levels (Fancy, Fancy Intense, Fancy Vivid, Fancy Deep, etc), red diamonds come in just one intensity level – Fancy - and they can only be modified by 3 colours: purple, orange or brown. Thus, red diamonds are only ever graded as Fancy Red, Fancy Brownish Red, Fancy Orangey Red, Fancy Purplish Red. While the Moussaieff Red hails from Brazil, most red diamonds today come from the Argyle Mine in Western Australia. Production has dropped significantly in the last decade and the Argyle Mine recently announced that they will close by 2021, thereby removing the world's foremost supplier of red and pink diamonds, which in turn will render those currently available even rarer. 

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Lot 656. A rare 1.66 carats heart-shaped fancy deep green diamond and diamond pendant. Estimate HK$ 1,600,000 - 3,000,000 (€ 170,000 - 330,000)© Bonhams 2001-2018

The heart-shaped fancy deep green diamond, weighing 1.66 carats, within a brilliant-cut diamond double surround, some of pink tint, completed by a box-link chain necklace, length 2.2cm.

Accompanied by a GIA report stating that the 1.66 carat diamond is Natural Fancy Deep Green colour. Report number 2165762062, dated 29 August 2017.

Note: On the spectrum of coloured diamonds, green diamonds are amongst the rarest. The green hue is the result of exposure to radiation deep in the earth's mantle over millions of years. Too much exposure to this radiation renders the stone black, while too little produces a pale or light green skin which disappears when the stone is cut. Thus, the odds of finding an aesthetically-pleasing green diamond are exceptionally low, while the odds of nature producing a green diamond with a deeper saturation are even lower. The largest and most famous green diamond is the 40.70ct "Dresden Green" which is a Natural Fancy Green. It came to public knowledge in the 1700s and is part of the German Crown Jewels. Deeper saturations in any size are exceptionally rare. 

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Lot 657. A rare 1.77 carats pear-shaped fancy dark grey-blue diamond and diamond ring. Estimate HK$ 1,600,000 - 3,000,000 (€ 170,000 - 330,000)© Bonhams 2001-2018

Of serpent design, the pear-shaped fancy dark grey-blue diamond, weighing 1.77 carats, pavé-set throughout with brilliant-cut diamonds, some of pink tint, diamonds approximately 2.00 carats total, ring size 5.

Accompanied by a GIA report stating that the 1.77 carat diamond is Natural Fancy Dark Grey-Blue colour and SI1 clarity. Report number 6183699669, dated 13 September 2017.

 

Note: Blue diamonds are extremely rare and are becoming rarer, with production dwindling to just a few dozen per year. For the last 100 years, the major source has been the Cullinan Mine in South Africa, while historically, blue diamonds have been found in India's Golconda mine which stopped producing diamonds over 300 years ago. 

Depending on the amount of boron captured inside the carbon structure during the diamond's initial formation deep within the earth's mantle millions of years ago, the resulting diamond will appear from a pale sunny sky blue to a deep ocean blue, with the more boron-heavy saturated blue being far more difficult to find than a pale blue type.

France's King Louis XIV was one of the first known people to fall in love with blue diamonds and the first reference in history to a blue diamond pertains to the 145 carat blue diamond he bought in the 1660s that would one day become the 45 carat Hope Diamond (graded Deep Greyish Blue) that now resides in the Smithsonian Institute in Washington DC. 

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Lot 654. A rare 10.03 carats oval-cut fancy brown-pink diamondEstimate HK$ 3,100,000 - 5,000,000 (€ 340,000 - 550,000)© Bonhams 2001-2018

The oval-cut fancy brown-pink diamond, weighing 10.03 carats, between a trapeze and tapered baguette-cut diamond shoulders, diamonds approximately 1.80 carats total, ring size 6

Accompanied by a GIA report stating that the diamond is Natural Fancy Brown-Pink colour and VVS1 clarity, with Excellent Polish and Symmetry. Report number 6272016241, dated 25 September 2017.

Also accompanied by an appendix from GIA stating that the diamond is Type IIa and therefore chemically pure. Dated 22 September 2017. 

Note: Pink diamonds are extremely rare. Approximately 1 in 10,000 carats of mined diamonds are gem quality fancy coloured diamonds and of this small amount, 0.01% are fancy pink diamonds with the majority of these having a characteristic secondary hue, such as purplish pink, orangey pink or brown pink. The main source of pink diamonds for the past 25 years has been the Argyle Mine in Western Australia which accounts for around 90% of pink diamond production today. Other sources have been India, several African countries, Brazil and Borneo. Most pink diamonds recovered are under 1ct and the largest pink diamond to come from the Argyle Mine is approximately 4 carats. With no major diamond discoveries in the last two decades and with the Argyle Mine poised to shut down by 2021, good quality, fancy pink diamonds of all sizes and colour combinations are expected to remain highly sought-after and increasingly difficult to find. 

Bonhams offers insights into how best to appreciate the different varieties of fancy coloured diamonds, which Graeme Thompson explains "have seen the greatest price gains in the past 10 years with fancy blue and fancy pink diamond prices rising the most due to the rapid reduction in supply. The value of yellow diamonds are increasingly on the rise while red and green diamonds are the rarest to be found."

Yellow Diamonds
After a dip in demand yellow diamonds, especially vivid yellows, are picking up again in popularity with many jewellery houses such as Tiffany's and Graff using them in their new collections.

Pink Diamonds
The Argyle Diamond Mine in Western Australia produces between 90 per cent and 95 per cent of the world's pink diamonds. However, as the mine's diamond seams are depleting fast with its estimated closure by 2021, large gem-quality pink diamonds from the mine are already in low supply and as such this means pink diamonds are becoming increasingly rare. 
Consequently, over the past 10 years, the price of pink diamonds has increased by 443% (source: Leibish & Co).

Green Diamonds
Fancy Green diamonds are among the rarest of all fancy coloured diamonds. The cause of colour in green diamonds is natural radiation from deep within the earth's surface. Green is the colour between blue and yellow, so diamonds of bluish green or yellowish green hue are a natural progression of colour that has become very collectible in recent years.

Blue Diamonds
Blue diamonds are the most sought-after natural colour diamonds and the supply and demand ratio makes them amongst the most expensive to purchase. 

According to The Robb Report, just 10 years ago, a buyer could have bought a vivid blue diamond for US$200,000 to US$300,000 per carat; today that same stone is fetching US$2 million to US$3 million per carat. This tenfold increase in value surpasses the growth rate of the FTSE 100 and the S&P 500 Index and also the housing market /real estate market.

There is only one source that continues consistently to produce the finest blue diamonds - the Cullinan Mine in South Africa - and their production has dwindled to a few dozen stones (if that much) a year.

A one carat vivid blue diamond can command roughly ten times more than a light-blue stone of the same size, according to the Fancy Colour Research Foundation, whose recent figures show that between 2006 and 2014, blue, pink, and yellow diamonds experienced an average appreciation of 154.7 per cent.

Red diamonds: 
Red diamonds are the rarest of all, and the largest in the world among them, The Moussaieff Red, is 5.11 carats, which was discovered in Brazil but these days most reds are coming from the Argyle Mine, albeit nothing nearly that size. Anything over one carat is considered large and incredibly rare today.