Many of us will know the unique rush of finding a designer jacket or pair of vintage Levi’s in a charity shop or car boot sale for a bargain price. So imagine how it must feel to buy a piece of costume jewellery for a tenner, only to realise it’s a seriously valuable diamond. The dream, right?
The owner, who doesn’t want to be identified, bought the “exceptionally sized” stone from a car boot sale at the West Middlesex hospital in Isleworth in west London.
She wore the stone, a 19th century 26 carat, cushion-shaped white diamond, daily for decades while doing everyday chores, completely unaware of its true value. (Good thing she didn't lose it down the sink while doing the washing up, eh?)
"The owner would wear it out shopping, wear it day-to-day. It's a good looking ring,” said Jessica Wyndham, head of the London jewellery department at Sotheby’s, where the stone will go under the hammer on 7th June.
"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.
"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."
The owner took it to Sotheby’s when a jeweller told her it might be valuable, and the auction house got it tested at the Gemological Institute of America.
It was the diamond’s “filthy” mount and lack of sparkle that had led the owner to believe it wasn’t a genuine gemstone for 30 years. But diamond cutting in the 19th century was generally "slightly duller and deeper" than today, meaning "it could trick people into thinking it's not a genuine stone,” Wyndham said.
In those days, cutters would work more with the crystal’s natural shape, “to conserve as much weight rather than make it as brilliant as possible."
What’s your most valuable car boot sale find?