De Beers and the Diamond Cartel

How De Beers controlled most of the world's diamond supply for much of the 20th century, created the "a diamond is forever" campaign, and how its grip weakened.

For much of the 20th century, De Beers controlled most of the world’s diamond supply.

Control

De Beers owned major mines and bought diamonds from others.
It controlled supply through its selling arm, releasing diamonds carefully to keep prices high.
At its peak, it controlled around 80 to 90 percent of rough diamond sales.

“A diamond is forever”

In 1947, De Beers’ ad agency created the slogan “A Diamond Is Forever”.
Campaigns made diamond engagement rings a tradition in the US and later Japan and elsewhere.
The slogan also discouraged reselling, protecting prices.

Weakening grip

New mines in Russia, Canada and Australia outside De Beers’ control.
Antitrust issues in the US and EU.
By the 2000s, De Beers shifted strategy and its market share fell to around a third.

Lab-grown threat

Cheap lab-grown diamonds further weakened pricing power.

Sale

Anglo American announced plans in 2024 to sell De Beers.

The engagement tradition

Before De Beers' campaigns, diamond engagement rings were less common. Advertising helped make them seem essential.

Thinking diamond prices reflect rarity alone

De Beers controlled supply and used advertising to support prices.

Key takeaways

De Beers controlled most diamond supply for decades.
It released diamonds carefully to keep prices high.
"A Diamond Is Forever" (1947) shaped demand.
New mines and lab-grown diamonds weakened its grip.