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Petra Diamonds Ltd is a diamond mining group headquartered in Jersey. Petra own one of the world's most productive mines historically, the Premier Mine is famed for having produced the Cullinan Diamond. It has the world's third-largest resource of diamonds. The company is listed on the London Stock Exchange.
The Cullinan kimberlite pipe is the second largest indicated diamond resource in the world by in-situ value. The current operating levels include the B-Cut at a depth of 747 metres, and beneath that lies the Centenary-Cut ("the C-Cut"), a world class diamond resource. The mine hosts a total resource of 202.1 million carats, including 16.5 million carats in tailings dumps.
The mine, previously known as Premier Diamond mine, is renowned for producing many of the world's largest and most famous diamonds, including the Cullinan Diamond, the world's largest gem diamond, at rough. Sir Thomas Cullinan, the former chairman of the Premier Diamond Mine, presented the Cullinan to England's King Edward VII in 1905. The Great Star of Africa, which sits in the Sceptre of the Crown Jewels, was produced from the Cullinan Diamond, and was until recently acknowledged to be the largest cut diamond in the world, weighing in at . In 1985 it lost the record to the Golden Jubilee, which was found in the same mine as the Cullinan and weighed in its polished state. More than a quarter of all diamonds weighing more than have originated from Cullinan. It is also the world's only significant source of Diamond color. One of these famous large blue diamonds was cut into several stones and made into a necklace which subsequently became known as the Cullinan Blue Diamond necklace. Exploring Africa's Gem Trail The Loupe GIA World News, Winter 2009
The Cullinan mine continues to produce large stones. The Cullinan Heritage, a white diamond, was discovered in September 2009. This stone was the 19th biggest uncut diamond ever found and was sold in February 2010 to Chow Tai Fook Jewellery for $35.5m, the highest price ever paid for an uncut diamond. The previous record was held by Gem Diamonds' Leseli La Letšeng, which was bought for $18.4m by Graff Diamonds in December 2008. Gem's biggest diamonds The Telegraph
Diamonds were first discovered on the Koffiefontein farm in 1870. Mining started in the form of small claims that were later amalgamated into Koffiefontein Mine Limited. De Beers acquired control of Koffiefontein Mine Limited in 1911. Mining operations were then continuous until the advent of the Great Depression in 1932 when work was suspended. Between 1950 and 1953, a prospecting shaft was sunk which was followed by limited production. The mine was reopened in 1970 and preparations for increased production were completed in August 1971. Immediately after completing the preparations, production from the open pit commenced and proceeded to a depth of 270 metres. Underground development started in 1974 through a sampling programme. Underground production briefly took place in 1982 but ceased soon thereafter due to the 1981 slump in the diamond market. These operations were resumed in March 1987. During the period 1972 to the end of 2004, approximately 69.5 million tonnes of kimberlite ore were mined and 6.1 million carats of diamonds were recovered. In February 2006, De Beers ceased mining when the old order mining right for Koffiefontein expired and in July of that year Petra Diamonds commenced operating the mine under care and maintenance conditions. The acquisition of the mine was completed in July 2007 and Petra Diamonds was subsequently able to commence diamond recoveries by starting to process the stockpile through the plant.
The Williamson Mine currently has a resource of 39.6 million carats (8,000 kg) (984 million tonnes of kimberlite). It has an average mining depth of 65 metres (90m at the deepest point) and a very low stripping ratio. Energy and Minerals Minister William Ngeleja said Petra's entry is "an opportunity to breathe new life into Williamson Mine and Tanzania's diamond mining sector." Mixed Outlook As Diamond Giant De Beers Sells Williamson Mine to Petra All Africa, 16 September 2008
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