Largest diamond ever auctioned sold for record $47.2 million

The largest diamond ever offered at auction went under the hammer in Geneva Tuesday evening for nearly $US34 million ($47.2 million), a world record for a gem of its kind, the Christie's auction house said.

A woman handles a 404 carat-rough diamond, discovered in early 2016 that has been transformed by de GRISOGONO Source: Getty Images

The 163.41-carat flawless D colour diamond, suspended from an emerald and diamond necklace called The Art of Grisogono, sold for 33.5 million Swiss francs ($US33.8 million), after taxes and commissions, at the Christie's autumn jewel auction.

This marks "a new world-record price for a D colour diamond at auction," Rahul Kadakia, auctioneer and head of Christie's international jewels division, told AFP.

The white, matchbox-size "Creation 1" diamond from Swiss jeweller de Grisogono weighs a whopping 163 carats.

The buyer was not immediately identified.

Australian diamond company Lucapa, which mined the stone originally measuring over 7 centimetres in length, says it was the largest diamond ever discovered in the African nation of Angola. The rough stone that it was cut from weighed 404 carats.

D is the highest colour grade attributed to a diamond, indicating that the stone is completely colourless, and thus extremely rare.

With a drawn-out round of rapid-fire bidding starting at 20 million francs, the necklace was finally sold to a telephone bidder, who wished to remain anonymous, for well above the asking price of 25 million.

'Masterpiece'

But some had expected The Art of Grisogono, which Christie's described as a "masterpiece of unparallelled beauty and exquisite workmanship", to fetch even more.

"I am disappointed that the Art of de Grisogono didn't sell for a more dazzling price," said Tobias Kormind, head of 77 Diamonds, a large European online diamond jeweller, who had said before the sale he thought the price might top $50 million.

The flawless, D colour 11A type diamond was cut from a 404 carat rough rock which was discovered in February 2016 in the Lulo mine in Angola -- the 27th biggest rough white diamond ever discovered.

The rough was analysed in Antwerp and cut in New York, where a team of 10 diamond-cutting specialists were involved in mapping, plotting, cleaving, laser-cutting and polishing the giant rough rock into a polished, flawless diamond.

A team from Swiss luxury jeweller de Grisogono then created 50 different designs around the 163.41-carat diamond, before opting for an asymmetric necklace with the stone as its centrepiece.

The left side of the necklace is made up of 18 emerald-cut diamonds and the right side composed of two rows of pear-shaped emeralds.