It's a slogan. During the 50's, Marilyn Monroe's - Diamonds Are a Girl's Best Friend album, made an impact by making diamonds more popular among girls with rising demands as well the price. Slogans have always been a good marketing tool for years now. A well researched slogan can influence the target audience for many years.
Yes
forever in blue jeans.
Disappeared - 2009 A Diamond Is Forever 6-11 was released on: USA: 4 February 2013
A female marketing executive at DeBeers created the tagline "a diamond is forever" around 1940 ... they have stuck with the slogan and successfully marketed it since that time.
A Pokemon adventure on Pokemon Diamond Verison can last forever if you wanted it to.
De Beers
I think it is Zale's jewelers.
De beers
No, you keep it forever.
One large heart diamond beneath a small heart diamond means "Love is forever"
Complete National Dex, it takes forever
This slogan began with DeBeers in the 1930s.