From the Feb 1982 issue of Atlantic Monthly, an article by Edward Jay Epstein on how diamonds became so popular and so valuable.
By 1941, The advertising agency reported to [De Beers] that it had already achieved impressive results in its campaign. The sale of diamonds had increased by 55 percent in the United States since 1938, reversing the previous downward trend in retail sales. N. W. Ayer noted also that its campaign had required “the conception of a new form of advertising which has been widely imitated ever since. There was no direct sale to be made. There was no brand name to be impressed on the public mind. There was simply an idea — the eternal emotional value surrounding the diamond.” It further claimed that “a new type of art was devised … and a new color, diamond blue, was created and used in these campaigns…. “
In its 1947 strategy plan, the advertising agency strongly emphasized a psychological approach. “We are dealing with a problem in mass psychology. We seek to … strengthen the tradition of the diamond engagement ring — to make it a psychological necessity capable of competing successfully at the retail level with utility goods and services….” It defined as its target audience “some 70 million people 15 years and over whose opinion we hope to influence in support of our objectives.” N. W. Ayer outlined a subtle program that included arranging for lecturers to visit high schools across the country. “All of these lectures revolve around the diamond engagement ring, and are reaching thousands of girls in their assemblies, classes and informal meetings in our leading educational institutions,” the agency explained in a memorandum to De Beers. The agency had organized, in 1946, a weekly service called “Hollywood Personalities,” which provided 125 leading newspapers with descriptions of the diamonds worn by movie stars. And it continued its efforts to encourage news coverage of celebrities displaying diamond rings as symbols of romantic involvement. In 1947, the agency commissioned a series of portraits of “engaged socialites.” The idea was to create prestigious “role models” for the poorer middle-class wage-earners. The advertising agency explained, in its 1948 strategy paper, “We spread the word of diamonds worn by stars of screen and stage, by wives and daughters of political leaders, by any woman who can make the grocer’s wife and the mechanic’s sweetheart say ‘I wish I had what she has.’”
It’s fascinating to watch the advertising beast change its tactics as the diamond monopoly’s needs shift with new supply, new markets, and unexpected success.