"Let's not kid ourselves, he's been groomed and trained for many years," says Eli Haas, president of the Diamond Dealers Club in New York. "He's a very capable, competent man - and of course the fact that he's an Oppenheimer doesn't hurt."
Yet Oppenheimer will be called on to represent the interests of the De Beers-Anglo American diamond and mining empire in ways his father and his father's father never dreamed of.
The Central Selling Organisation, the London-based De Beers marketing arm formed by Sir Ernest to protect diamond prices, regulated the distribution and price of the world's uncut diamonds for the greater part of this century. Now it is under threat as producers worldwide consider bypassing the cartel. Some already have.
In September, after a year-long dispute, Russia's diamond-marketers and producers agreed to sell $550m (pounds 329m) of uncut diamonds, half their annual production, through the CSO each year. But the agreement expires in 13 months. If it is not extended, Russian mines, the second-largest diamond producers in the world, will be free to sell all their output directly, or "leak" to big diamond markets such as Tel Aviv.
"His role will be to put a different face on this monopoly and present the case of De Beers in more human terms," says Martin Rapaport, publisher of the Rapaport Diamond Report in New York. "De Beers has been seen as having taken too much, if not all, of the pie."
Oppenheimer brings to the chairman's post extensive knowledge of the diamond and mining business, a reputation for sound leadership and the security that comes from having been bred to lead the De Beers empire, a web of more than 100 companies with interests in six continents.
It is widely expected that one day he will also be named chairman of Anglo American Corporation, the precious metals and industrial company founded by Sir Ernest in 1917 that owns 32.5 per cent of De Beers.
He has been chairman of the Central Selling Organisation for the past 13 years. Just last month, he was also named chairman of Anglogold, Anglo American's new gold company.
"I don't like the word cartel," he once said of the CSO. "It has a connotation of exploitation." He prefers "producers' co-operative".
Oppenheimer has worked in the family business all his life. He began his career as personal assistant to his father, who waschairman from 1957 to 1984, and occupied various posts in the De Beers-Anglo American empire, primarily in the Anglo gold division and the diamond side.
He grew up on the family estate in South Africa and was educated in England atHarrow and Oxford.
The Russians are not the only opponents he now has to contend with. The New York-based World Federation of Diamond Bourses, the association that represents about 25 diamond exchanges around the world, recently passed a resolution criticising the CSO's monopoly.
Opposition has emerged in other parts of the world, too. Last year Australia's Argyle Mine, part-owned by Rio Tinto, the world's largest mining company, broke away and marketed its output alone. Argyle was previously responsible for 6 per cent of CSO sales.
De Beers is also worried that some new Canadian mines, the Broken Hill Proprietary-Diamet Lac de Gras, located just south of the Arctic Circle, will not join the CSO when they begin production in about a year.
The company must also cope with flagging sales due to the slump in Asian economies. Last week, De Beers Centenary AG said sales of uncut diamonds in the second half of 1997 fell 16 per cent to pounds 1.06bn compared with the same period last year.
Also unclear is the impact of the recently announced restructuring of Anglo American and De Beers. In November, Anglo American's gold operations were split off to form a separate business unit. In Christmas week the group's diamond interests were also split off.
While the diamond selling organisation is under threat, Oppenheimer is taking steps to ensure that the dynasty endures. His son is clearly being groomed in the family tradition. Educated at Harrow and Oxford, 28-year-old Jonathan Ernest Oppenheimer now works in Harare, Zimbabwe for Anglo American.