Set into an asymmetric necklace designed by de GRISOGONO and offered on 14 November at Christie's in Geneva, this 163.41 carat, flawless D-colour emerald-cut diamond is the largest ever to come to auction.
The necklace, named The Art of de Grisogono, sold for $33.5m - $29.5m plus $4m premium - exceeding pre-sale predictions of $30m.
Sotheby's holds the record for the most expensive diamond ever auctioned, having sold the 59.6-carat Pink Star for $US71 million to Hong Kong-based jewellery retailer Chow Tai Fook.
The rough was analyzed in Antwerp and cut in NY, 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.
The colourless diamond was taken from a 404-carat stone found in Angola.
The necklace is made of 18 diamonds on one side and two rows of pear-shaped emeralds on the other.
It has since passed through the hands of famous French jeweler Frederic Boucheron and later the Baron von Derwies.
Christie's jewel auction, which raked in sales totaling 105.4 million Swiss francs, will be followed Wednesday by a similar auction at Sotheby's.