De Beers UK (formerly known as The Diamond Trading Company) is the sales and marketing jewel of diamond-mining giant De Beers SA -- a  joint venture of De Beers and the government of Botswana. De Beers UK supplies almost half of all the rough diamonds on the market. It receives diamonds primarily from Botswana, Namibia, and South Africa. De Beers UK participates in 50-50 joint ventures with the governments of Botswana and Namibia to sell diamonds from those countries. After sorting and valuing the diamonds, the company sells the gems to clients, or sightholders. On the marketing side, the De Beers UK promotes diamonds through such programs as the well-known "A Diamond Is Forever" advertising campaign.