(IDEX Online) - Petra has recovered a huge Type IIb blue diamond from its Cullinan mine, in south Africa.The 39.34 carat gem (pictured) is significantly larger than any of the five that formed the Letlapa Tala Collection, from the same deposit, which fetched $40.36m last November.They ranged from 27.75-cts to 9.61-cts and were bought jointly by De Beers and the South African wholesaler and manufacturer Diacore.The newly-recovered stone is said to be of "exceptional quality" due to its color and clarity.It is to be sold at a special tender, said the London-based miner.