Diamond Worth Up To £10m Boosts British Firm

A 232.08-carat white diamond, recovered from a mine that produced gems for the Crown Jewels, could fetch a value of up to $16m (£10m).

The estimate was made by analysts after Petra Diamonds (LSE: PDL.L - news) , which bought the Cullinan mine in South Africa from De Beers, showed off the rough stone.

Petra's share price soared 7% on the FTSE 250 in the wake of the announcement, even though the company declined to put an estimate on the stone.

The find is not Petra's largest white diamond.

In 2009 it unearthed a flawless 507-carat diamond, also at the Cullinan mine. The diamond was known as the Cullinan Heritage and fetched $35.3m - a record price for the company.

It was from the same mine in 1905 that the largest rough gem diamond was recovered, the 3,106 carat Cullinan Diamond which was cut into stones for the Crown Jewels housed at the Tower of London.

It was made into the First Star of Africa - mounted at the top of the Sovereign's Sceptre - and the Second Star of Africa, a 317-carat polished diamond which forms the centrepiece of the Imperial State Crown.

Petra said it expected the new white diamond, of "exceptional size and clarity", to be sold before the year's end.

Its investors are also awaiting the outcome of the sale of a rare 122.52-carat blue diamond recovered from Cullinan this year.

Analysts have pegged the stone's value at more than $35m (£21.7m).