De Beers and the Engagement Ring That Was Invented in 1947

In 1938, fewer than ten percent of American engagement rings contained a diamond. The stones were considered showy, impractical, and — for most of the working middle class — completely irrelevant to the act of getting married. A ring with a coloured stone, or no stone at all, was perfectly normal.

By 1990, more than eighty percent of American engagement rings had a diamond at the centre. The "two months' salary" rule was treated as common sense. Couples who skipped a diamond were quietly judged by friends and parents.

Almost none of that happened by accident. It was the deliberate output of a single advertising campaign, commissioned by a single company, designed to solve a very specific business problem: De Beers had warehouses full of diamonds and not enough buyers.

The cartel that needed Americans to believe

By the 1930s, De Beers controlled roughly ninety percent of the world's rough-diamond supply. The cartel had been built quietly over decades through acquisitions of South African mines and exclusive purchase agreements with new ones. The model worked beautifully when demand was high. It nearly broke the company when demand collapsed during the Great Depression.

Diamond prices had fallen by half. European royalty, the historical buyers of large stones, had largely stopped buying. The American market was the only one with any growth left, and Americans simply didn't think of diamonds as essential to anything. De Beers needed to invent a reason for them to.

In 1938, De Beers's chairman Harry Oppenheimer travelled to New York and hired a small Philadelphia advertising agency called N. W. Ayer & Son. The brief was, in retrospect, extraordinary. De Beers did not want to advertise its own brand. It did not want to advertise specific products. It wanted to change the way Americans thought about marriage.

The campaign

The agency's strategy, formalised in a 1939 memo, has been studied by marketers ever since. There were no coupons, no discounts, no point-of-sale promotions. Instead, the agency would pursue a coordinated, multi-decade cultural intervention.

Hollywood actresses were given diamonds to wear at premieres. Magazines were fed staged photos of celebrities receiving and showing off diamond engagement rings. Schools received "marriage education" packets that mentioned the diamond as a normal part of the proposal. Newspaper society pages were briefed on which couples had recently bought diamonds and which had not. Lecturers were paid to give talks at high schools about the proper way to get engaged.

The campaign worked, slowly at first and then with real momentum. By the mid-1940s, the share of American engagement rings containing diamonds had crept up from nearly zero to about thirty percent.

In 1947, an Ayer copywriter named Frances Gerety, working late on a deadline, scribbled a tagline at the bottom of a draft layout. The four words she wrote that night — A Diamond Is Forever — would be used by De Beers continuously for the next seventy years and would, in 1999, be named by Advertising Age the slogan of the century.

The tagline mattered for two reasons. It told consumers that the diamond was permanent, transcendent, beyond the reach of price comparison. And it told them, more quietly, that diamonds were not to be resold. A market for second-hand diamonds — which would have devastated retail prices — never developed at scale, because the cultural meaning of the diamond made selling it feel like selling the marriage.

The two-months-salary rule that was also invented by an ad agency

By the 1970s, the next problem De Beers faced was that the diamond purchase had become culturally normal but the average ring was getting cheaper. Buyers were trading down. The cartel needed Americans to spend more.

In the early 1980s, De Beers commissioned a new campaign — this one centred on a number. The "two months' salary" guideline appeared in advertisements, in jewellery-store training materials, and in articles in bridal magazines. There was no historical, religious, or even folk basis for the figure. It was a marketing invention, designed to anchor the customer's price reference at a level the cartel preferred.

The number worked. Subsequent surveys showed that the "two months' salary" rule was widely believed by American buyers to be traditional. In Japan, where De Beers ran a parallel campaign, the number was set at three months. In both cases, average spend per engagement ring rose toward the anchored figure within a decade.

What the campaign actually proved

The De Beers diamond campaign is held up as the textbook case of manufactured demand because of its scale, its longevity, and the completeness of its success. But the more interesting lesson for any operator studying it is what it reveals about the nature of consumer "tradition" itself.

Most of what we believe about how things have always been done is, on inspection, neither old nor universal. The white wedding dress, the surprise engagement, the diamond ring, the "two months' salary" rule — all of these are recent inventions, and most of them were invented because someone had inventory to move.

De Beers's modern competitive position has weakened considerably. The cartel structure cracked in the 2000s as new producers (notably the Russian state and Australian and Canadian miners) began selling outside the De Beers channel. Lab-grown diamonds, which are physically and optically indistinguishable from mined diamonds, have flooded the market and collapsed wholesale prices. De Beers's actual share of supply is now well under fifty percent.

But the cultural infrastructure they built still works. The diamond is still the default. The two months' salary anchor is still discussed at jewellery counters. Generations of couples still believe a ring without one would be incomplete.

The most successful brand-building exercise of the twentieth century created, more or less from scratch, a tradition that almost everyone now thinks predates them. That is the campaign's real achievement, and it is not undone by the fact that the company that ran it is no longer the company it was.