The advertising slogan "A diamond is eternal" is used by De Beers in 1939.
De Beers is a cartel and multinational company in the world diamond industry, which controls 40% of the global diamond mining and trade through one-stop service. De Beers was founded by Cecil Rhodes in 1888. Now the company is headquartered in Luxembourg and is a private company. DTC, a subsidiary of its group, is responsible for marketing.
De Beers' main business includes diamond ore mining, trade, industrial diamond production and processing. Diamond mining in De Beers includes open-pit mining, underground mining, large alluvial deposits, coastal mining and deep-sea mining. The mining areas are located in Botswana, Namibia, South Africa and Canada.
References:
Baidu encyclopedia-De Beers