A diamond ring bought for £10 at a London boot sale is expected to sell for £350,000 at Sotheby's

Rebecca Smith
Diamonds are forever - even if you pick them up at a car boot sale
Diamonds are forever - even if you pick them up at a car boot sale (Source: Getty)

One man's trash is another man's treasure, as they say.

And so it turned out for the owner of a diamond ring that they picked up at a car boot sale for £10 30 years ago, which is expected to fetch £350,000 at auction.

Read more: A pair of mismatched diamond earrings have sold for a record-breaking £44m

They had thought the "exceptionally sized" stone was a piece of costume jewellery when buying it at West Middlesex Hospital, west London, in the 1980s.

However, in actual fact it was a 26 carat, cushion-shaped white diamond from the 19th century. And the owner wore it daily for decades none the wiser. She took it to Sotheby's when a jeweller told her the stone could be valuable.

The £10 diamond
The £10 diamond (Source: Sotheby's)

Now, the stone will be going under the hammer at Sotheby's. The auction house said it will be offered as part of its fine jewels sale on 7 June.

The head of Sotheby's London jewellery department, Jessica Wyndham, said it was bought as a costume jewel so "no one had any idea it had any intrinsic value at all".

"This is a one-off windfall, an amazing find," she added.

The owner had been to a series of car boot sales over the years but didn't have a past of collecting antiques, nor diamonds.

Wyndham said as the older style of diamond cutting was "slightly duller and deeper" than today, it could trick people into thinking it's not a genuine stone.

Still, while that's a diamond find, it's not quite on the scale of a sale earlier this month. A pair of diamond earrings sold for a record-breaking £44m and they didn't even match. The earrings which were different colours, were sold as individual lots, and went for $57.4m (£44.3m) altogether. The flawless 14.5-carat "Apollo Blue" diamond sold for $42.1m, while the 16-carat pink "Artemis Diamond" went under the hammer for $15.3m.

Read more: Gem Diamonds' shares sparkle with 114-carat diamond find

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