A diamond is forever.

“A diamond is forever” was coined in 1947 by American copywriter Frances Gerety while working at N.W. Ayer & Son on the De Beers account. The line was created for a U.S. advertising campaign aimed at strengthening the association between diamonds and engagement, especially in the post–World War II consumer boom. De Beers’ strategy emphasized diamonds as enduring symbols rather than commodities, discouraging resale and encouraging the idea of a permanent, emotionally charged purchase. The slogan quickly became one of the most influential advertising lines of the 20th century and helped cement the modern cultural expectation of a diamond engagement ring.

The phrase works by fusing a physical claim (diamonds are extremely durable) with a moral and emotional one (true love and commitment should be permanent). “Forever” shifts the diamond from a luxury good to a timeless emblem, implying that the relationship it represents ought to be as lasting as the stone. The slogan also subtly reframes economic behavior: if the diamond is “forever,” it is not meant to be traded back into the market, but kept as an heirloom and proof of devotion. Its power lies in compressing romance, durability, and social expectation into four simple words.

“Diamonds are forever.”
“Diamonds are forever, forever, forever.”