Sotheby's auction in London sold a ring bought for £10 at an Isleworth car boot sale for £656,750 after a 26.27‑carat diamond was identified. The ring, purchased in the 1980s by a woman who never suspected its hidden value, had been worn daily for thirty years, its tarnished silver‑gold setting masking a gem of extraordinary size.
In 2017 the owner brought the ring to a local jeweller, who immediately sensed something off. The jeweller measured an unusually large stone and called Sotheby's, sparking a chain of expert evaluations.
Jessica Wyndham, Sotheby's Head of High Jewelry in Europe, explained that the stone weighed 26.27 carats, was cushion‑cut, color I and clarity very, very slightly included. She added, "If you've always believed something isn't valuable, there's little reason to question it." The Gemological Institute of America confirmed the details, noting the cut dates back to the nineteenth century.
Bidding at the auction was fierce. Two objects—this ring and a Cartier brooch once worn by Margaret Thatcher—captured the crowd's attention, but the ring ultimately drew a final hammer price of £656,750. The sale exceeded expectations, with the proceeds earmarked for the Endeavour Fund.
The ring's owner, who still frequents car boot sales, said she now searches for signatures on mounts, hoping to spot hidden treasures. "It's a reminder that history can be in the most ordinary of places," she told a reporter.
Sotheby's said the case illustrates the importance of expert scrutiny for antiquated jewellery. Specialists advise looking for stamps and maker marks, as these clues help gauge a piece's age and quality.