The ironic story behind the slogan "a diamond is forever" 💍


	May 7, 2025

Credit: mevans/ iStock

The woman who coined the slogan "A Diamond Is Forever" never married.

Much like the durable gems it refers to, the advertising slogan "A Diamond Is Forever" has endured the test of time. The line was first penned in 1947 and cemented a connection between diamond rings and romance, though it was, ironically, conceived of by a woman who never married, opting instead to prioritize her career and spend time with her dogs.

Mary Frances Gerety was a copywriter at the N.W. Ayer & Son advertising agency, where she was assigned to De Beers, a company that controlled the global supply of rough diamonds. At the time, diamonds weren't as widely associated with love as they are today — before World War II, only an estimated 10% of proposals featured a diamond engagement ring. Many women tended to prefer more practical engagement gifts, such as a car or washing machine. It was up to Gerety to change that perception by convincing couples that diamond rings weren't just a luxury, but an essential part of a marriage proposal.

While working late on an ad campaign for the company, Gerety realized she'd forgotten to come up with a memorable slogan. According to The New York Times, Gerety later recalled, "Dear God, send me a line," and jotted down the now-iconic phrase before heading to bed. When she awoke the next morning, she thought the slogan was passable but nothing special. But those four simple words, "A Diamond Is Forever," proved to be hugely successful. U.S. diamond sales skyrocketed from $23 million in 1939 to an astounding $2.1 billion by 1979. Gerety's creation was later named the top slogan of the 20th century by Ad Age.

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"Diamonds Are a Girl's Best Friend" was first performed by Carol Channing.

The song "Diamonds Are a Girl's Best Friend" was popularized by Marilyn Monroe in the 1953 film Gentlemen Prefer Blondes — a musical performance later ranked as the 12th best in film history by the American Film Institute. But the song was originally sung by actress and comedian Carol Channing, who debuted it on the stage four years earlier. Channing starred as Lorelei Lee in the original 1949 Broadway production of Gentlemen Prefer Blondes. The show featured music by Jule Styne — who also scored Gypsy and Funny Girl — and lyrics by Leo Robin, who won an Oscar for the 1938 song "Thanks for the Memory" from the Bob Hope film The Big Broadcast of 1938. Together, the pair composed "Diamonds Are a Girl's Best Friend," which was made famous by Channing during a nearly two-year Broadway run. Channing performed her signature song once again in the 1974 Broadway show Lorelei — a spinoff of the original 1949 musical.