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 (USD 33.8 million, 28.7 million euros), after taxes and commissions, at the Christie's autumn jewel auction.
Previously, Christie's set an auction record in May 2016 with the sale of a 14.62-carat diamond known as the "Oppenheimer Blue" for $50.6m (£34.7m).
"Early spectrographic testing at the Gemological Institute of America in NY declared the stone to be a D-colour, Type IIA diamond - a variety highly valued for its transparency and colour", Christie's stated in a press release. The rough stone, the largest ever discovered in the African country, originally weighed 404 carats and measured over 7 centimetres in length. Experts, however, are bitterly disappointed as they had expected the diamond to be sold for at least £12 million more.
A team of 10 specialists in NY cut the jewel from a rough 404-carat stone discovered in Angola previous year, the biggest diamond ever found in that country. Ten diamond-cutting specialists worked on the rough in NY after it was analysed in Antwerp.
The diamond, the centrepiece of an asymmetric gem-studded necklace designed by Fawaz Gruosi, founder of Geneva jeweller De Grisogono, exceeded the auction house's expectation of US$25 million. It is set to go under the hammer in Geneva today evening, with bids expected to top Dollars 25 million. 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.
Christie's said the seller was a private collector, but did not reveal their identity.