"A Diamond Is Forever" is one of the most famous and enduring advertising slogans in the history of marketing, and it is closely associated with the diamond industry, particularly with De Beers. This slogan was created by the advertising agency N.W. Ayer & Son for De Beers in 1947.

Here's an explanation of the slogan:

1. A Diamond: This part refers to the diamond itself, which is one of the hardest known natural materials and is prized for its brilliance and rarity. Diamonds have been traditionally used in engagement rings and other fine jewelry.

2. Is Forever: This phrase suggests that a diamond is timeless and enduring. It implies that, like true love, a diamond will last forever. This association of diamonds with eternal love and commitment has been a central theme in diamond marketing.

The "A Diamond Is Forever" campaign was highly successful because it not only emphasized the intrinsic qualities of diamonds but also created a powerful emotional connection between diamonds and romantic commitment. It helped establish the tradition of using diamonds in engagement rings and contributed to the perception that diamonds are a symbol of everlasting love.

The campaign had a significant impact on the diamond industry and played a pivotal role in maintaining the desirability and value of diamonds. It is still recognized and associated with De Beers and the diamond trade, demonstrating the enduring power of a well-crafted advertising slogan.