Not fully true but they are dominant in S-Africa along with Consolidated Gold. There are plenty of diamonds around, the issue is quality for the gem market....... The Russians are the other major players.....back in the 80s when officially SA was under sanctions, the Chairman of de Beers was photographed at the Bolshoi Ballet.......Was on Panorama.
The other factor affecting diamond prices which have firmed over 30% in the last 2 years and doubled in 5, has been the impact of the Chinese and Far East markets - there is a huge clamour for diamonds of all grades, be it a 4 carat SI emerald cut or industrial diamonds for drill bits.