Two exquisite colourless diamonds lead the way, both bearing the signature of one of the world’s most renowned diamantaires: Harry Winston. The first is an impressive 32.42- carat diamond belonging to the same rare category as the ‘Apollo Blue’: Type IIb diamonds. It is also D Colour - the most sought-after grading for white diamonds - and the GIA has declared that, after minor re-polishing, the stone has the potential to be Internally Flawless (Lot 326, Estimate CHF 1,510,000 – 2,510,000 / US$ 1.5 – 2.5 million). 

Also signed Harry Winston, a second D Colour diamond is sure to captivate connoisseurs, thanks to its graceful marquise shape. Weighing 16.92 carats, the diamond is also of extraordinary purity: it also has the potential to be Internally Flawless following minor re- polishing (Lot 325, Estimate CHF 1,110,000 – 1,910,000 / US$ 1.1 – 1.9 million). 

Accompanying these two captivating diamonds is a superb emerald and diamond ring, also by Harry Winston, set with a stunning step-cut stone weighing 21.34 carats. According to the SSEF, this fabulous gemstone is of Colombian origin – the most sought-after of all the world’s known sources of emeralds – and shows no indications of treatment to modify the clarity: “The described emerald exhibits a remarkable size and weight of 21.34 carats, combined with an attractive and homogeneous green colour and a fine purity... In addition to these qualities, this emerald shows no indications of clarity modification in fissures, which is a further sign of rarity". (Lot 315, CHF 165,000 – 225,000 / US$ 160,000 – 220,000). 

The collection also features an extraordinary sapphire from Burma, weighing 45.74 carats. This captivating stone, set in a ring by Van Cleef & Arpels, is described by the Swiss Gemmological Institute (SSEF) as exhibiting ‘an impressive size and weight of 45.74 carats, combined with an exceptional purity and attractive well saturated blue colour... (which) poetically also referred to as ‘royal blue’, is due to a combination of well-balanced trace elements in the gemstone, which are typical and characteristic for fine sapphires from Mogok, Burma’ (Lot 312, Estimate CHF 810,000 – 1,410,000 / US$ 800,000 – 1,400,000). 

First patented by Van Cleef & Arpels and a feat of jewellery craftsmanship, the house’s technique known as ‘serti mystérieux’ (or ‘mystery setting’) is a method of gem-setting where the prongs are invisible. The technique can require as much as 300 hours of work per piece and the stunning effect can be seen in a delightful group of jewels in this extraordinary collection. They include this ruby and diamond brooch of floral design (Lot 318, Estimate CHF 82,000 – 122,000 / US$ 80,000 / 120,000). 

OUTSTANDING COLOURLESS DIAMONDS
The spring auction will offer a very attractive selection of outstanding colourless diamonds, including a superb diamond ring by Van Cleef & Arpels set with a step-cut diamond weighing 21.60 carats. The GIA has certified that the diamond combines two coveted features: it is of Type IIa and D Colour – the most sought-after grading for white diamonds and that the stone has the potential to be Internally Flawless, subject to minor re-polishing (Lot 372, Estimate CHF 1,610,000-2,010,000 / US$ 1,600,000-2,000,000). This extraordinary pear-shaped diamond weighs an impressive 34.41 carats and also boasts D Colour (Lot 369, Estimate CHF 940,000 – 1,250,000 / US$ 935,000 – 1,245,000). 

EXTRAORDINARY COLOURED GEMSTONES
Sapphires from Kashmir are widely regarded as the finest in the world, and collectors participating in our May sale will have the opportunity to admire several very fine examples. For example, this superb sapphire weighing 11.64 carats, which the SSEF has described as displaying the sought-after ‘royal blue’ colour. The institute’s experts also praised the stone’s ‘well-proportioned shape and cut combined with excellent purity’ (Lot 340, Estimate CHF 1,310,000 – 1,910,000 / US$ 1.3 – 1.9 million). 

This beautiful ring features a cabochon-shaped Kashmir sapphire weighing 9.79 carats, signed by Tiffany and Co. This piece is noteworthy also for its interesting provenance: it was formerly in the collection of Sophia Augusta Brown, granddaughter of Nicholas Brown Jr., co-founder of the prestigious Brown University in Rhode Island (Lot 360, Estimate CHF 405,000 – 610,000 / US$ 400,000 – 600,000). 

The mesmerising beauty of emeralds from Colombia has long been cited as the most desirable by lovers of fine jewels. In the presence of this striking ring by Harry Winston features an exceptional step-cut emerald weighing 14.49 carats, is isn’t hard to see why (Lot 173, Estimate CHF 305,000 – 505,000 / US$ 300,000 – 500,000). 

JEWELS WITH NOBLE PROVENANCE
This year, Sotheby’s Geneva is proudly celebrating ten years of dedicated sales of jewels with Noble and Aristocratic provenance, following the launch of biannual sales in 2007.