My favorite passage from the article:
De Beers needed a slogan for diamonds that expressed both the theme of romance and legitimacy. An N. W. Ayer copywriter came up with the caption “A Diamond Is Forever,” which was scrawled on the bottom of a picture of two young lovers on a honeymoon. Even though diamonds can in fact be shattered, chipped, discolored, or incinerated to ash, the concept of eternity perfectly captured the magical qualities that the advertising agency wanted to attribute to diamonds. Within a year, “A Diamond Is Forever” became the official motto of De Beers.
In 1951, N. W. Ayer found some resistance to its million-dollar publicity blitz. It noted in its annual strategy review:
The millions of brides and brides-to-be are subjected to at least two important pressures that work against the diamond engagement ring. Among the more prosperous, there is the sophisticated urge to be different as a means of being smart…. the lower-income groups would like to show more for the money than they can find in the diamond they can afford…
To remedy these problems, the advertising agency argued, “It is essential that these pressures be met by the constant publicity to show that only the diamond is everywhere accepted and recognized as the symbol of betrothal.”