Final answer:
The largest producer of diamonds by value is the South African company De Beers, which continues to hold a significant position in the global diamond market.
Step-by-step explanation:
The world's largest producer of diamonds by value is the South African company De Beers, which was founded by Cecil Rhodes. Established in 1888, by a year later, Rhodes controlled 90% of the world's diamond production. De Beers has been influential in the diamond industry, with operations extending beyond South Africa to countries including Botswana, Namibia, and Canada. The company not only has mining and production operations but also directs a worldwide distribution network of rough diamonds. Despite facing increased competition in recent years, De Beers maintains a significant presence in the diamond market, still selling about 35% of the world's diamonds today.