In the 1980s, a London shopper paid £10 for a diamond ring at a car boot sale; 30 years later, its 26.27-carat stone sold for £657,000 at auction

Sometimes, an ordinary second-hand purchase can turn out to be far more precious than its buyer ever imagined. A woman from Isleworth, west London, found this when a ring she had bought for just £10 at a car boot sale in the 1980s was discovered as a genuine diamond worth hundreds of thousands of pounds.

After wearing the ring for years without knowing its true value, the woman eventually sold it at Sotheby's in London for £656,750 ($849,637). The final cost was nearly twice the auction estimate of £350,000, making the ring an remarkable example of a surprising discovery.

A £10 ring with an extraordinary secret

The woman bought the ring at a car boot sale held at West Middlesex Hospital in the 1980s. Believing it to be costume jewellery, she wore it regularly without suspecting that its stone was a precious diamond.


Named the "Tenner," the ring showcases a 26.27-carat, cushion-shaped white diamond believed to have been cut in the 19th century. As per the BBC, the diamond's earlier history, that includes how it came to be sold at the car boot sale, continues to be unknown.

The ring's appearance gave the owner small reason to suspect its value. Jessica Wyndham, head of Sotheby's London jewellery department, described that the stone was set in a "filthy" mount and did not sparkle noticeably. Its appearance made the buyer regard it as a decorative accessory rather than a precious gemstone.

The exposure of the real value of the diamond

But the ring's extraordinary story took a turn when a jeweler suggested it could be valuable. The owners then took it to Sotheby’s, where specialists studied the stone and arranged for testing by the Gemological Institute of America (GIA).The institute confirmed the stone was a real diamond.

The owners arrived at the auction house not knowing the potential worth of the ring, said Wyndham.

Speaking to the Evening Standard in May, Wyndham emphasized the potential impact of such a surprising financial advantage.

Wyndham also cited that the owner had attended many car boot sales over the years but had not collected antiques or diamonds.

Why the antique diamond looked different

The ring's understated appearance was partly described by its traditional cutting style. The older cutting approach prioritised retaining the natural crystal's weight rather than increasing the stone's brilliance. Consequently, the diamond did not reflect light as strongly as a contemporary cut might, helping describe why its value went unrecognised for so long.

The final auction price exceeded expectations

Before the sale, Sotheby's estimated that the ring could fetch up to £350,000. The total amount was however £656,750, well above the expectations.

The result showed the difference in the price paid for the ring in the 1980s and what it finally cost at auction.A £10 buy which was thought to be costume jewelry became a sale of over £650,000 after its true identity was confirmed.

Also Read: A shopper paid $25 for a Victorian brooch at an antiques market in 2024; experts identified William Burges’s work, and the piece later sold for $15,000 at auction

A £10 buy that turned into an unexpected find

The story of the Tenner, from a car boot sale to a major auction, exposed how the significance of an object can be hidden for years. Its owner wore the ring as daily jewellery, unaware that its stone was a genuine diamond believed to date from the 19th century.

Only after a jeweller raised the possibility of its value did the owners seek professional assessment. Later examination and GIA confirmation identified the stone, thus making it available for sale at Sotheby’s.

While the diamond’s previous history is a mystery, its auction result of £656,750 sealed the ring’s position as an exceptional find. The amazing result of a day-to-day object proving to be worth more than expected was shown in a £10 buy in the 1980s which went for almost twice its estimate.