In 1938, a De Beers representative wrote to the ad agency N. W. Ayer & Son, asking if “the use of propaganda in various forms” could juice the engagement-ring market. In 1947, the N. W. Ayer copywriter Frances Gerety coined the slogan “A Diamond Is Forever,” and ever since then, diamond engagement rings have been all but mandatory—an $11 billion industry in America as of 2012.
