On 13 March 1888, De Beers Consolidated Mines Ltd. was founded to exercise control over virtually all diamond production in South Africa. The company was registered in Kimberley, and was the merger of the De Beers Mining Company and Kimberley mines under the Kimberley Central Diamond Mining Company - managed by Barney Barnato.
Diamonds were discovered in 1860 on De Beer's farm, in proximity of Kimberley, a town which was later to be established. Two mines were dug on the premises and were once the world's most productive diamond mines. In 1871, Cecil John Rhodes bought a claim to the mine at De Beer's, which marked the beginning of his dominance of the diamond mining industry in South Africa.
De Beers expanded to include the Dutoitspan, Bultfontein and Wesselton diamond mines, which resulted in the development of a comprehensive system. More diamonds were produced and soon underground mining took the place of open mines.
Sir Ernest Oppenheimer became the chairman of De Beers in 1929, and steered the company through the Great Depression. New diamond deposits were discovered near Lichtenburg in the North West Province, and in Little Namaqualand.
Oppenheimer also marketed diamonds internationally with the help of the Central Selling Organisation (CSO), which had also been created by Rhodes as the London Diamond Syndicate in 1890. The CSO controlled nearly 80% of global diamond trade by the late 1980s, but reduced demand resulted in its replacement by the Diamond Trading Company (DTC) in 2000.
Harry Oppenheimer assumed his father's position in 1957, and expanded De Beers' holdings by buying the diamond pipe at Postmasburg from Finsch Diamonds, and by playing a role in the mining of marine diamonds off the coast of Namibia.
De Beers was one of the first South African companies to address the HIV/AIDS issue by sponsoring drug treatment for its employees. The company has continued to influence the availability and price of diamonds globally, and has been accused of unfair trading practices.
The biggest shareholder in De Beers Consolidated Mines Ltd. is Anglo American PLC. Today the company remains the biggest producer and distributor of diamonds in the world, and has interests in synthetic diamonds, minerals, ores and mining, and processing equipment.