A Diamond is Forever

"A Diamond is Forever" This is one of the most successful sales copy in the world. It was created by De Beers, the biggest diamond mining company. If people keep diamonds forever the prices wouldn't drop down forever. If they sell their diamonds to secondhand markets too much the prices would fall down. That's the real meaning for it. De Beers and other mining companies are carefully making the market price of diamond. 

In Japan, lots of men buy a diamond ring for engagement. They say the groom should spend three times as much as his monthly salary to buy it. It's also a De Beers's sales copy in 1968. They did the campaign only in Japan.