A diamond ring bought at a car boot sale for £10 has been sold for £656,750 at auction in London.
The jewel was expected to fetch £350,000, but went for almost double that at Sotheby’s on Wednesday.
The owner believed the “exceptionally-sized” stone was a piece of costume jewellery when she bought it at West Middlesex Hospital in Isleworth, west London, in the 1980s.
Unaware it was a 26 carat diamond, she wore it daily for decades.
The cushion-shaped white diamond is thought to have been from the 19th Century.
A diamond ring bought at a car boot sale for £10 has been sold for £656,750 at auction in London.
The jewel was expected to fetch £350,000, but went for almost double that at Sotheby’s on Wednesday.
The owner believed the “exceptionally-sized” stone was a piece of costume jewellery when she bought it at West Middlesex Hospital in Isleworth, west London, in the 1980s.
Unaware it was a 26 carat diamond, she wore it daily for decades.
The cushion-shaped white diamond is thought to have been from the 19th Century.
Ahead of the sale, the head of the auction house’s London jewellery department, Jessica Wyndham, said: “The owner would wear it out shopping, wear it day-to-day. It’s a good looking ring.
“No-one had any idea it had any intrinsic value at all. They enjoyed it all this time.”
Ms Wyndham said the owner – who does not want to be identified – assumed it was not a genuine gemstone because it was in a “filthy” mount and it did not have the sparkle of a diamond.
It wasn’t until after 30 years of wearing the ring that the owners took it to Sotheby’s and a jeweller told them it may be valuable.
John Axford, Asian art expert at Woolley & Wallis auctioneers, confirmed the “excellent investment” bore the four-character mark of Qianlong – the sixth emperor of the Qing dynasty – and would have been made in the palace workshop between 1736 and 1795.
The firm sold the vase in Salisbury in November 2016, where it made £61,000, including buyer’s premium. That was double its guide price of £30,000.