Petra Diamonds sold a 507-carat diamond for $35.3 million yesterday, breaking a record as the highest price EVER paid for a rough diamond. Analysts had estimated the value of the stone, one of the 20 biggest high-quality rough diamonds in the world, at around $25 million. AIM-listed Petra found the gem last September at its 74percent owned Cullinan mine in South Africa, which it bought from sector giant De Beers in 2007. The Cullinan mine has been the source of many large diamonds, including the world’s largest rough diamond — the Cullinan — at 3,106 carats. That gem was cut into the Star of Africa stones that are now set in Britain’s Crown Jewels. The question is, what rapper is going to thry to get their hands on this one????