'Tenner' Diamond Purchased For Just $10 Sells At Sotheby's For $850000

Also sold on the day of the auction was a Cartier diamond brooch worn by Margaret Thatcher on a number of high-profile public occasions, including the day she offered her resignation as Prime Minister to The Queen.

The jewel was purchased 30 years ago at a vehicle boot sale at West Middlesex Hospital in Isleworth, west London. And, if you're still in your seat, the individual who originally purchased the ring for the low price assumed it was a piece of costume jewelry.

Sotheby's Fine Jewels hosted the auction for the 26 carat diamond ring that was purchased in the 1980s from a auto boot sale for $13, assuming it was costume jewelry.

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".

Although rare, similar cases of grossly undervalued items found at the likes of flea markets and garage sales, have occurred in the past.

The 26.29-carat cushion-shaped, claw-set diamond ring had been bought from a auto boot sale, according to Sotheby's auction house.

The 26.27 carat diamond is thought to have been cut in the 19th Century but its full history is unknown. "This wouldn't have looked like that. The silver had tarnished and there was probably some dirt", Wyndham added.

Even more shocking, the final selling price of almost $900,000 is likely to go up.

One expert, Tobias Kormind, said: "It originates from the 1800s - before the discovery of modern diamond mines and a time when very few diamonds were available".

'The new owner is likely to re-cut it into a modern diamond that will emit even more sparkle and potentially be worth a multiple of the Sotheby's estimate'.

  • Zachary Reyes