What's the real reason diamond engagement rings became so popular, and is it actually just a marketing trick?

The short answer is yes, the dominance of diamond engagement rings is largely the result of one of the most successful marketing campaigns in modern history, though the full story has some nuance worth exploring. Before the 20th century, diamond engagement rings were not a widespread tradition. Some wealthy Europeans exchanged them, but most people used other gemstones or simple bands. The shift began in 1938 when De Beers, the South African diamond mining conglomerate that controlled roughly 90 percent of the world's diamond supply, hired the advertising agency N.W. Ayer to solve a serious business problem. Diamond prices had collapsed during the Great Depression, and De Beers needed to stimulate demand. The agency's strategy was not just to sell diamonds but to fundamentally reshape how Americans thought about love, commitment, and what an engagement should look like. They placed diamonds in movies, got them on the wrists of celebrities, and worked with fashion magazines to present them as the ultimate symbol of romance. In 1947, copywriter Frances Gerety came up with the slogan "A Diamond Is Forever," which De Beers adopted and ran for decades. It became one of the most recognized advertising slogans ever created and did something clever beyond just selling jewelry. It discouraged people from reselling diamonds by associating them with eternal love, which conveniently kept the secondhand market suppressed and maintained the illusion of scarcity and value. The campaign worked extraordinarily well. By the 1950s, the diamond engagement ring had become a cultural expectation in America, and De Beers then exported the same strategy to other countries. Japan had virtually no tradition of diamond rings before De Beers launched a targeted campaign there in the 1960s and 70s. Within two decades, Japan became the second largest diamond engagement ring market in the world. The same playbook was used in Germany, Brazil, and elsewhere. This demonstrates that the tradition is not some ancient human instinct but a manufactured norm that spread within living memory through deliberate commercial effort. There is also the matter of diamonds not actually being as rare or valuable as their price suggests. De Beers maintained high prices for most of the 20th century by carefully controlling supply, stockpiling diamonds and releasing them slowly to prevent market flooding. The resale value of diamonds is notoriously poor. A diamond ring bought at retail will typically sell for a fraction of its purchase price on the secondhand market, which is the opposite of what you would expect from a genuinely scarce and precious commodity. The idea that you should spend two months salary on an engagement ring is itself another De Beers invention from their advertising, a completely arbitrary benchmark they promoted to increase the average transaction size. That said, there are a couple of counterpoints worth acknowledging. Humans have always used symbolic objects to mark important life transitions, and the desire to give something beautiful and meaningful during a proposal is genuine even if the specific form that desire takes was shaped by advertising. Some people genuinely love diamonds for their appearance and find real meaning in the tradition regardless of its origins. Cultural practices do not become meaningless simply because they were commercially promoted at some point. Christmas gift giving was also heavily shaped by commercial interests in the 19th and 20th centuries, but that does not make the warmth people feel during the holiday fake. The more important takeaway is probably about consumer awareness and choice. Many couples today are opting for alternative gemstones like sapphires, emeralds, or moissanite, or choosing lab-grown diamonds which are chemically identical to mined ones but cost a fraction of the price. The ethical concerns around mined diamonds, including the history of conflict diamonds and environmental damage from mining, have also pushed people toward alternatives. The tradition is not going away entirely, but understanding its origins gives people the freedom to make choices based on what actually matters to them rather than what a century of advertising has conditioned them to believe is necessary. The diamond industry spent billions convincing the world that love requires a specific rock from the ground, and for a long time it worked almost perfectly. Knowing that history is genuinely useful when you are standing in a jewelry store deciding how to express something as personal as a marriage proposal.