Ernest Oppenheimer was the first of the Oppenheimer family to prosper in the diamond industry. He and his descendants would continue to play an integral role in shaping the industry for more than a century. He was born in 1880 in Freidburg, Germany, the son of a cigar merchant. At the age of 17, he began his working career as a diamond broker in London as diamonds were just becoming widely available with the early South African diamond rush. By 1902, he had impressed his employers so much that they sent him to South Africa to represent them as a diamond buyer in Kimberley.
At the same time, the massive Premier Mine was put into production. Its owner, Thomas Cullinan, had refused to join De Beers Consolidated mining, and instead began selling his production to two independent diamond dealers from London, Oppenheimer and his brother Bernard. This massive production undermined De Beers' sales, but Francis Oats, the successor to Cecil Rhodes as Chair of De Beers, was dismissive of the threat. However, production from the Premier Mine would soon eclipse the production from all De Beers mines combined. Oppenheimer was appointed as the local agent for the powerful London syndicate, much to the angst of Oats.