De Beers is the company that single-handedly made the diamond industry what it is today. De Beers was founded by Cecil Rhodes, who also founded the state of Rhodesia which later became Zambia and Zimbabwe. The Rhodes scholarship is also named after him, and funded by his estate. De Beers has mines in Botswana, South-Africa, Namibia and Canada. Because of this, the company practically has a monopoly on diamonds and can truly be called the largest diamond corporation in the world. For more information, click here.