(BBC News) A rare blue diamond has been unearthed at a mine in South Africa.
The 25.5-carat stone was recovered by Petra Diamonds at its Cullinan mine and is expected to bring large profits.
Experts say it could be worth more than $10m (£6m), and the find gave a boost to Petra's share price.
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Similar finds in recent years from the Cullinan mine have commanded high prices and Petra, with operations in Botswana and Tanzania, is expecting a high level of interest from buyers.