Sir Ernest Oppenheimer was born in Friedberg, Hesse, Germany, the son of Edward Oppenheimer, a cigar merchant. Oppenheimer began his working life at 17 when he entered Dunkelsbuhler & Company, a diamond brokerage in London. His efforts impressed his employer and in 1902, at the age of 22, he was sent to South Africa to represent the company as a buyer in Kimberley, where he eventually rose to the position of mayor from 1912 to 1915. In this role, he helped raise the manpower for the Kimberley Regiment for service during World War One.
He became great friends with William Lincoln Honnold, an American engineer and chairman of Transvaal Coal Trust, Brakpan Mines, Springs Mines and The New Era Company.
In 1917, they launched the Anglo American Corporation with financial assistance from J. P. Morgan. The initial capital was £1 million. Half of the capital was subscribed in America and half in England and South Africa. He would remain as a permanent director and its chairman until 1953. In 1919, two years after its launch, Anglo American purchased diamond mines in South West Africa which would pose a challenge to the De Beers diamond business monopoly.
He took part in the 1924 South African general election and was elected to the House of Assembly as the Member for Kimberley. He held the seat until 1938. In 1927, Ernest Oppenheimer managed to wrest control of Cecil Rhodes's De Beers empire and built and consolidated the company's global monopoly over the world's diamond industry until his retirement. He gained the chairmanship of De Beers in 1929.
He died in Johannesburg in 1957. He was born into a Jewish family, but, as an adult, he converted to Anglicanism and was buried at St George's Church, Parktown.
According to en.wikipedia