Diamond producer Petra Diamonds has raised £205m ($325m) from a placing at 150p a share to fund the $210m (£132m) purchase of the Finsch diamond mine in South Africa from De Beers.Finsch is South Africa's second largest diamond mine by production and will be Petra's eighth producing mine. It's expected to turn out over 1.5 million carats per annum (Mctpa) in its first full year of production, increasing to 4 Mctpa by the 2014 financial year and to more than 5 Mctpa by 2019.The purchase of Finsch, which has a diamond resource of 48.1m carats (Mcts) and 26.6 Mcts of reserves, increases Petra's gross resource base to about 309 Mcts with a gross attributable in-situ value of around $38bn."We believe that Petra offers an exceptional growth profile at a time when there is a very positive outlook for our industry and a strong rough diamond price environment," boss Johan Dippenaar said.