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Biggest ever diamond sold at auction fetches £25.5 million

The Art of de Grisogono, a necklace suspending a 163.41-carat, D color, flawless, IIA type diamond (REUTERS/Denis Balibouse)

A gemstone described as the “most beautiful diamond in the world” has sold for a stunning £25.5 million at auction.

The 163.41 carat flawless D-colour emerald-cut diamond was auctioned off at Christie’s in Geneva, and had an original guide price of £23m. It is the biggest ever diamond to be sold at auction.

Experts, however, thought it could have gone for even more, with some predicting before the sale it could fetch £37m.

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In the end, the diamond, set in an emerald necklace for a piece of jewellery called The Art of de Grisogono, sold to an anonymous telephone bidder.

The flawless 163-carat flawless emerald stone, was the largest of its kind ever to be put up for auction (Actua Films via AP Images)

The stone was 404.20 carats when it was a rough diamond mined in eastern Angola on 4 February last year.

It is the largest diamond ever found in Angola and the 27th largest rough white diamond ever discovered.

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A team of more than 10 specialists from the Julius Klein Group in New York transformed the rough diamond into the final cut and polished gem.

Diamond cleaver Ben Green started working on splitting the rough diamond in two in June last year.

A staff member poses with “Le Grand Mazarin,” which was also part of the Christie’s sale in Geneva (REUTERS/Denis Balibouse)

It took the 80-year-old six months to polish the diamond down into an emerald-cut. According to Christie’s, that work on finishing the diamond took some 1,700 hours.

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The Art of de Grisogono was the highlight of the Christie’s Magnificent Jewels auction which generated an astonishing $106,070,751 in sales.

Also on the block was Le Grand Mazarin, a 19-carat pink diamond that once belonged to King Louis XIV, Napoleon Bonaparte and other French rulers.

It sold for 12.5 million Swiss francs (£10.98m), obliterating the pre-sale estimate.