Nope, they're victims of succesful marketing campaign by De Beers. https://en.wikipedia.org/wiki/Engagement_ring#20th_century https://en.wikipedia.org/wiki/Enga

Nope, they're victims of succesful marketing campaign by De Beers. https://en.wikipedia.org/wiki/Engagement_ring#20th_century https://en.wikipedia.org/wiki/Engagement_ring#20th_century In 1938, the diamond cartel De Beers began a marketing campaign that would have a major impact on engagement rings. During the Great Depression of the 1930s, the price of diamonds collapsed.[25] At the same time, market research indicated that engagement rings were going out of style with the younger generation. Before World War II, only 10% of American engagement rings contained a diamond.[26] While the first phase of the marketing campaign consisted of market research, the advertising phase began in 1939. One of the first elements of this campaign was to educate the public about the 4 Cs (cut, carats, color, and clarity). In 1947 the slogan "a diamond is forever" was introduced.[27] Ultimately, the De Beers campaign sought to persuade the consumer that an engagement ring is indispensable, and that a diamond is the only acceptable stone for an engagement ring.