In 1938, with the Depression still strangling luxury spending and Europe sliding towards war, the young Harry Oppenheimer travelled from Johannesburg to New York with a problem. His family's company, De Beers, controlled almost all of the world's diamond production, yet Americans — the last big market standing — were buying fewer and smaller stones. The advertising agency he engaged, N.W. Ayer & Son, came back with a proposal that has shaped weddings ever since: stop selling diamonds as gems or investments. Sell an idea instead — that a diamond is the only acceptable token of betrothal, that its size measures a man's love, and that no proposal is complete without one. De Beers had already been reduced to closing mines to prop up prices; what it needed now was demand, manufactured as carefully as supply.
The awkward truth the campaign had to bury was that diamonds are not especially rare. They had seemed so for centuries, while a trickle arrived from India and Brazil. Then, in 1867, a stone later named the Eureka turned up near South Africa's Orange River, and the rushes that followed uncovered diamonds in industrial quantities. At Kimberley, Cecil Rhodes worked his way up from renting water pumps to miners to buying their claims, and in 1888, with Rothschild backing, he founded De Beers Consolidated Mines — named after the two brothers on whose farm diamonds had been found. Within a few years the company controlled some ninety per cent of world production, and it understood its real business perfectly: not digging diamonds up, but keeping them scarce. Rough stones flowed through a single London channel, later known as the Central Selling Organisation, where hand-picked dealers took the box they were offered or stopped being invited.
A diamond is forever
Ayer's campaign worked through every channel America had: planted newspaper stories about celebrities' rings, film stars loaned ever larger stones, even lecturers sent into schools to instruct girls in the new tradition. In 1947 a young copywriter named Frances Gerety, finishing a night's work, scrawled the line "A Diamond Is Forever". It became the company's permanent signature, and in 1999 Advertising Age named it the advertising slogan of the twentieth century. The genius of "forever" was double. It promised eternal love, and it quietly discouraged resale — for nothing would puncture the mystique faster than millions of second-hand diamonds, which fetch a fraction of their retail price, flooding back onto the market. The campaign also invented the salary rule: one month's pay was the early American benchmark, later inflated to two. By the time Marilyn Monroe sang "Diamonds Are a Girl's Best Friend" in Gentlemen Prefer Blondes in 1953, the invention had become culture.
The trick travelled. From the mid-1960s De Beers's advertising turned to Japan, where the diamond engagement ring had essentially no tradition, and sold it as a badge of modern, Western-style life; within a generation the ring went from a rarity among Japanese brides to the norm, Japan became one of the world's largest diamond markets, and the salary benchmark was set locally at three months' pay. When vast Soviet deposits were found in Siberia in the 1950s, De Beers protected the cartel by quietly agreeing to market Soviet output — and absorbed the resulting flood of small stones by promoting a new product, the "eternity ring".
The invention unravels
The phrase "the diamond invention" comes from the American writer Edward Jay Epstein, whose 1982 investigation — including the pointed essay "Have You Ever Tried to Sell a Diamond?" — laid out the machinery of manufactured scarcity. The cartel itself proved mortal. For decades De Beers executives avoided setting foot in the United States for fear of antitrust prosecution; in 2004 the company pleaded guilty to price-fixing in a US court and paid a $10 million fine to normalise its position. By then mines in Australia, Canada and post-Soviet Russia were selling outside the cartel, De Beers had abandoned its role as buyer of last resort, and its market share slid from roughly ninety per cent towards a third. Laboratory-grown diamonds, chemically identical to mined ones, now attack the scarcity story from another direction.
Yet the tradition holds. Romantics point out that the first recorded diamond engagement ring long predates the advertisements: Archduke Maximilian of Austria gave one to Mary of Burgundy in 1477. True — but that was a princely gesture, not a rule for everyone. The universal expectation, the months of salary, the stone as proof of devotion: all of it was drafted in an advertising agency within living memory. The stones were real; the tradition was manufactured — and it has outlived the monopoly that made it.
Quiz nuggets
- Cecil Rhodes founded De Beers Consolidated Mines in 1888, named after the brothers whose South African farm sat over the diamond diggings.
- Copywriter Frances Gerety of N.W. Ayer coined "A Diamond Is Forever" in 1947; Advertising Age named it slogan of the twentieth century in 1999.
- Marilyn Monroe sang "Diamonds Are a Girl's Best Friend" in the 1953 film Gentlemen Prefer Blondes.
- The first recorded diamond engagement ring was given by Archduke Maximilian of Austria to Mary of Burgundy in 1477.
- De Beers pleaded guilty to price-fixing in a US court in 2004, paying a $10 million fine.