Courtesy Sotheby's
A diamond ring purchased for ‎£10 ($13) sold for £656,750 ($847,667) at the Sotheby's Fine Jewels auction in London.
JUSTIN TALLIS/AFP/AFP/Getty Images
The ring sold for roughly double its initial estimated value of £250,000 ($325,000) to £350,000 ($456,000).
courtesy christies
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Christies Images Ltd 2016
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courtesy sotheby's
'The Unique Pink' is the largest Fancy Vivid pink pear-shaped diamond to ever be offered at auction.
courtesy sotheby's
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Bloomberg/Bloomberg/Bloomberg via Getty Images
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Sotheby's
Sotheby's auctioned this 9.54 carat ring it says belonged to child star Shirley Temple on April 19, 2016. Though it was expected to fetch between $25 million and $35 million, it failed to sell.
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This 12.03-carat blue diamond fetched $48.4 million at auction on November 11, 2015. It was previously the world's most expensive price-per-carat diamond sold.
FABRICE COFFRINI/Getty Images
The fancy, vivid blue diamond was discovered in South Africa in January last year.
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This 118.28 oval white diamond became the largest sold at auction when it went for $30.6 million at a Sotheby's auction in 2013.
Courtesy Sotheby's
In April 2015, a 100-carat, emerald cut, D color, internally flawless diamond -- the largest of its clarity and cut to ever be shown at auction -- sold for $22 million.
FABRICE COFFRINI/AFP/Getty Images
The 76.02-carat 400-year-old Archduke Joseph diamond set a new record for price per carat for a colorless diamond in 2012, when it sold for $21.5 million at a Christie's auction.
Courtesy Chow Tai Fook
In 2010, Hong Kong's largest jewelry retailer, Chow Tai Fook, bought one of the world's largest rough diamonds for $35.3 million.
Courtesy Chow Tai Fook
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Story highlights

A diamond ring purchased for £10 ($13) has sold for £656,750 ($847,667)

The ring was purchased at a car boot sale in the 1980s

The owner of the ring assumed it was a piece of costume jewelry

CNN  — 

A diamond ring purchased for ‎£10 ($13) has sold for £656,750 ($847,667) – roughly double its initial estimated value of £250,000 ($325,000) to £350,000 ($456,000) – at the Sotheby’s Fine Jewels auction in London last night.

The 26-carat ring was first purchased in the 1980s by an anonymous seller, who bought the jewel at a car boot sale, under the assumption that it was a piece of costume jewelry.

The startling realization of the ring’s true value came decades later, when the wearer chose to have the ring appraised by a local jeweler. The ring was later identified as a cushion-shaped diamond set in a 19th century mount.

JUSTIN TALLIS/AFP/AFP/Getty Images
A member of Sotheby's staff holds the diamond at Sotheby's auction house in London.

A diamond in the rough

The ring first made headlines in May when Sotheby’s revealed its estimated value of £250,000 ($325,000) to £350,000 ($456,000) – already a far cry above its initial purchase price.

According to Jessica Wyndham, head of Sotheby’s jewelry department, the ring’s true value is particularly surprising because the mount and cut are unrecognizable to the modern day wearer.

“When we think of diamonds, we think of modern cuts, of brilliance,” she told CNN in May, noting that the diamond was cut in a particularly old-fashioned style and the ring mount had darkened over time.

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“This wouldn’t have looked like that. The silver had tarnished and there was probably some dirt. These diamonds were made for candlelight, not our white artificial light, so it was all about trying to bring out its fire.”

Mysterious origins and future worth

Although Sotheby’s did not name the identity of the buyer, the auction house did reveal that the ring was purchased as international trade within the industry, and not by a private collector.

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Tobias Kormind, diamond expert and managing director of 77 Diamonds, predicts the ring’s £656,750 ($847,667) final selling price is only a fraction of what it may one day be worth.

“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 today’s price,” he said in a press release.

“I’m convinced the £10 ($13) ring was once owned by royalty or a person of great wealth, because it originates from the 1800s – before the discovery of modern diamond mines and a time when very few diamonds were available.”

Unexpected treasures

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

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In March 2013, a ceramic bowl purchased for $3 at a yard sale sold for a whopping $2.2 million at an auction in New York. In March 2014, a golden egg purchased as scrap metal was later discovered to be a $33 million Faberge egg previously owned by Tsar Alexander III.