Blue diamonds are extremely rare. Their color is caused by the presence of boron impurities—the more boron, the deeper the blue. The 29.6-carat stone was recovered by Petra Diamonds at its Cullinan mine, about 40km (25 miles) north-east of Pretoria. This stone is one of the most exceptional stones recovered at Cullinan during Petras operation of the mine, the company said. bbc.co.uk/news/world-africa-25838015
Posted on: Thu, 23 Jan 2014 16:10:55 +0000
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