'Exceptional' blue diamond found could be worth £50m when cut

Blue stones are more valuable than their white counterparts, and when diamonds are cut they are worth considerably more. The 120 carat Peacock Brooch, made up of a number of coloured diamonds was priced at £58 million ($100 million).

The mine is the site of the world’s largest certified diamond find – the 3,106-carat Cullinan – which was found in 1905. It was cut to form the Great Star of Africa and the Lesser Star of Africa, set in the Crown Jewels of Britain.

Petra, the London-listed firm which acquired the mine in 2008, said tests were still needed on the “exceptional stone” to determine its value. The company confirmed it would not be sold before June 30.

A spokesman for Petra said: “The rarity of a blue diamond of this magnitude sets it apart as a truly significant find.”

Petra sold a 29.6-carat blue diamond for almost £15 million ($25.6m) in February and a 25.5-carat one for £10 million ($16.9m) last year. The Star of Josephine diamond, found in 2008, sold for £5.6 million ($9.5 m) after it was found in 2008.

Petra rose 5.3 per cent to 176 in early trade following the find, the highest intraday (within a day) level for more than two years.

Last year The Pink Star, a 59.6-carat oval cut pink diamond set a world record for the highest price paid at auction for a diamond after it sold for 76.3 million Swiss francs (£49 million).

But auction house Sotheby’s was forced to buy back the flawless diamond earlier this year after the buyer defaulted on the payment.

The Pink Star was cut and polished from a 132.5 carat rough diamond mined by De Beers in Africa in 1999.

Sotheby’s still holds the world record price for a diamond sale after another pink diamond – the 24.78-carat Graff Pink – sold for £27 million ($46m) at auction.

more