The Diamond Empire: Oppenheimer family's cartel, Artificial scarcity (Video)
Source: video.google.com
De Beers is able to create an artificial scarcity of diamonds through its wholly-owned Central Selling Organization (CSO), thus keeping prices high. A cartel is a group of formally independent producers whose goal is to increase their collective profits by means of price fixing, limiting supply, or other restrictive practices. The US oil and gasoline markets work the same way seeking to restrict the flow of IRAQI oil for example.