<P> De Beers used its dominant position through the 20th century to influence the international diamond market . The company used several methods . Firstly, it convinced independent producers to join its single channel monopoly . When that did not work, it flooded the market with diamonds similar to those of producers who refused to join in . Lastly, it purchased and stockpiled diamonds produced by other manufacturers in order to control prices by limiting supply . </P> <P> In 2000, the De Beers business model changed because of factors such as the decision by producers in Canada and Australia to distribute diamonds outside the De Beers channel, as well as rising awareness of blood diamonds that forced De Beers to "avoid the risk of bad publicity" by limiting sales to its own mined products . De Beers' market share of rough diamonds fell from as high as 90% in the 1980s to 33% in 2013, because of a more fragmented diamond market bringing greater competition, as well as more transparency and greater liquidity . In November 2011, the Oppenheimer family announced its intention to sell all its 40% stake in De Beers to Anglo American plc, thereby increasing Anglo American's ownership of the company to 85% (the other 15% is owned by the Government of the Republic of Botswana). The transaction was worth £ 3.2 billion (US $5.1 billion) in cash and ended the Oppenheimer dynasty's 80 - year ownership of De Beers . </P> <P> Mining in Botswana takes place through the mining company Debswana, a 50--50 joint venture with the Government of the Republic of Botswana . It operates four mines--Jwaneng, Orapa, Letlhakane and Damtshaa, though Damtshaa was put on care and maintenance in 2015 . </P> <P> In Namibia, mining is carried out through Namdeb Holdings, a 50--50 joint venture with the Government of the Republic of Namibia . Namdeb Holdings is made up of Debmarine Namibia (covering offshore mining) and Namdeb Diamond Corporation (land - based coastal mining). For offshore mining, motor vessels are used, including the sixth and latest, the N $2.3 billion SS Nujoma, the world's most advanced diamond exploration and sampling vessel, which began full operations in June 2017 . </P>

Do they mine diamonds in the united states