A superb 3.81 carats fancy intense blue diamond ring. Estimate £1,300,000-1,800,000. Photo: Bonhams.

LONDON.- A pair of Kashmir sapphires and a rare blue diamond are set to sparkle at Bonhams London as it kicks off the autumn auction season with its Fine Jewellery sale on Tuesday 20 September. 

Headlining the sale is a stunning oval-cut blue diamond. Weighing 3.81 carats, the Fancy Intense Blue diamond is accompanied by a GIA report and hails from a private British collection. It is estimated at £1,300,000-1,800,000. 

Jean Ghika, Head of Jewellery for Bonhams UK & Europe, says: “Blue diamonds are extraordinarily rare and account for only 0.004% of all diamonds mined. This particular diamond is categorised as a Fancy Intense Blue with no modifying or secondary colour. With so few blue diamonds coming to auction we are anticipating global interest.” 

Bonhams has a strong track record of selling blue diamonds and holds price-per-carat world auction records for both a Fancy Deep blue diamond at $1.77m per carat[1], and a Fancy Greyish-Blue diamond at $730,000 per carat[2]. 

A pair of late 19th century 8.97 and 8.93 carats Kashmir sapphire and diamond cluster earrings. Estimate £1,300,000-1,800,000. Photo: Bonhams. 

An exceptional pair of late 19th century Kashmir sapphires is another top lot to go under the hammer at the 20 September sale which starts at 2pm in Bonhams London’s New Bond Street salesroom. 

The cushion-shaped sapphires weigh 8.97 and 8.93 carats and are accompanied by reports from AGL and SSEF laboratories[3] stating that both sapphires were found to be of Kashmir origin, with no evidence of heat treatment. Estimated at £400,000-600,000, the sapphires display a saturated and vivid blue colour. 

Jean Ghika adds: “Sapphires hailing from Kashmir display a velvety quality and a rich blue tone unique to the region. They are among the most highly-prized gems for serious collectors and investors. Kashmir sapphires are extremely rare; after the discovery of the mine in the high Himalayan mountain region of northwest India in 1881 the majority of mining activity took place during the following decade, after which the supply was essentially exhausted.“ 

Bonhams London recently sold a pair of Kashmir sapphire earrings weighing 7.92 and 7.96 carats for £1,538,500 in its December 2015 sale. 

Jean Ghika continues: “In recent years we have seen a growing demand from our global collectors for top quality coloured diamonds and gemstones. We are looking forward to showcasing the blue diamond, the Kashmir sapphires and a number of our other selected lots in London, New York and Geneva during our pre-sale previews."

A superb 3.81 carats fancy intense blue diamond ring. Estimate £1,300,000-1,800,000. Photo: Bonhams.