Tanzania government moves diamond sorting office home from London Tanzania has closed down the London offices of its diamond sorting firm and transferred its operations to Dar es Salaam. March 23, 2010 Tanzania has closed down the London offices of its diamond sorting firm and transferred its operations to Dar es Salaam. Commissioner of Minerals in the Ministry of Energy and Minerals Dr Peter Dalaly Kafumu said the closure followed Petra Diamonds acquisition of De Beerss interest in the Williamson Diamond mine. Dr Kafumu said that since Petra sells diamonds abroad directly, there was no need for the Tanzania Diamond Sorting (Tansort) operation in London, according to the East African newspaper. Petra bought a 75 percent stake in Williamson Diamond Mine from De Beers in 2008 for $10 million and changed the firms name to Williamson Diamond Ltd. The Tanzanian government owns the other 25 percent. Tansort, established in 1966, assessed the price of diamonds exported to the United Kingdom from the Williamson Diamond mine, and collected five percent royalty on behalf of the government.