During the 20th century, De Beers used several methods to leverage its dominant position to influence the international diamond market. Firstly, it convinced independent producers to join its single channel monopoly. When that did not work, it flooded the market with diamonds similar to those of producers who refused to join in. It purchased and stockpiled diamonds produced by other manufacturers as well as surplus diamonds in order to control prices by limiting supply. Finally, it bought diamonds when prices fell considerably, such as during the Great Depression.