According to reports, the cushion-shaped white diamond was cut in the 19th century, before being bought by the anonymous owner at a sale in London in the 1980s. The owner has worn the ring “daily” for the past three decades, believing it to be costume jewellery.
The diamond has since been given a Gemological Institute of America (GIA) colour grade of I and clarity grade of VVS2.
Sotheby’s London jewellery department head Jessica Wyndham was reported as stating that “no-one had any idea it [the diamond] had any intrinsic value at all,” adding the way the stone was cut “could trick people into thinking it's not a genuine stone".
"With an old style of cutting, an antique cushion shape, the light doesn't reflect back as much as it would from a modern stone cutting,” Wyndham said. “Cutters worked more with the natural shape of the crystal, to conserve as much weight rather than make it as brilliant as possible."
The diamond ring was expected to sell for between £250,000 (AU$435,000) and £350,000 (AU$609,000) at the Sotheby’s Fine Jewels auction in London on 7 June.
Jeweller takes a look
According to Professional Jeweller, jeweller Mark Guess from L Guess Watchmaker & Jewellers in Middlesex was responsible for identifying the value of the diamond.
Guess was said to have offered to assess the ring after the stone’s owner – a regular customer – had mentioned they were looking to find out its value.
“I basically told [the owner] what they have is a life changing ring, which I estimate to be possibly hundreds of thousands [of dollars],” Guess stated, reportedly also suggesting Sotheby’s as an auction venue.
As previously reported by Jeweller, another item purchased at a car boot sale also made headlines in the past. A watch purchased for about US$30 (AU$40) and later identified as the Breitling Top Time timepiece worn by James Bond in the movie Thunderball sold at a Christie’s auction for US$160,175 (about AU$214,977) in 2013.
update - diamond sells, exceeds estimates
On 7 June, the diamond ring – dubbed the ‘Tenner’ in reference to its original price – sold at the Sotheby’s Fine Jewels auction in London for £656,750 (AU$1.1 million), effectively smashing pre-sale estimates.
A Cartier diamond brooch worn by the late UK Prime Minister Margaret Thatcher also sold at the same auction.
Commenting on the results, Wyndham noted both pieces had been the subject of intense interest.
“It was a thrill to bring the hammer down on two objects which have been the subject of so much attention over the last few weeks, and to see that translate into such strong bidding competition,” she said.
According to reports, an anonymous international buyer made the successful bid for the Tenner diamond ring.
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