Petra Diamonds has celebrated the sale of a 29.62 carat blue diamond for 25.56m dollars. The diamond, which was discovered in the Cullinan mine in South Africa in January, was hailed as one of the most important blue diamonds ever recovered.Chief Executive of Petra, John Dippenaar, said: "An additional allure is the diamond's heritage from the Cullinan mine in South Africa, which is well known as the source of many of the world's most spectacular diamonds, including the two main diamonds in the British Crown Jewels, and which is the world's most important source of very rare blue diamonds."The group's share price was up 1.22% at 149.80p following the announcement. NR