A large diamond ring purchased for £10 at a car boot sale is expected to fetch £350,000 under the hammer at Sotheby’s July auction.
The ring, which was bought 30 years ago for £10 when the original owner had mistaken it for a piece of costume jewellery, has been described by Sotheby’s as a 26.27ct, cushion-shaped, white diamond stone.
It is said the original owner may have thought it was a CZ due to 19th Century diamonds not being cut to show off their brilliance like today’s gems.
The auction house’s head of London jewellery department Jessica Wyndham told the Press Association: “The owner would wear it out shopping, wear it day-to-day. It’s a good looking ring but it was bought as a costume jewel. No-one had any idea it had any intrinsic value at all. They enjoyed it all this time.”
Wyndham continued: “They’d been to quite a few car boot sales over the years. But they don’t have any history of collecting antiques and they don’t have any history of collecting diamonds. This is a one-off windfall, an amazing find.”
After around 30 years of wearing the ring, the owners bought it into Sotheby’s after a jeweller told them it could have substantial value.
Sotheby’s got the stone tested at the Gemological Institute of America.
The diamond is thought to have been cut in the 19th Century but its history and how it arrived at the car boot sale, is unknown.
“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,” explained Wyndham. “Cutters worked more with the natural shape of the crystal, to conserve as much weight of the crystal rather than make it as brilliant as possible. The older stones have quite a bit of personality, they sparkle in a different way.”
The diamond ring will be offered as part of Sotheby London’s Fine Jewels sale, on July 7.