Final answer:
Cecil Rhodes, a British colonizer, founded the De Beers Diamond Company in 1888 and controlled 90% of the world's diamond production by 1889. His company influenced the global diamond market significantly and played a role in the colonial expansion in Southern Africa.
Step-by-step explanation:
The renowned British colonizer who owned De Beers Diamond company was Cecil Rhodes. He founded De Beers in 1888 and by the following year, he controlled an astounding 90% of the world's diamond production. This company had a significant impact on global diamond production, with mining operations across multiple African nations and exploration activities around the world. Despite growing competition in recent years, De Beers was once the major player in the diamond industry, maintaining its monopoly until the start of the 21st century. It was also influential in the creation of colonies in Southern Africa, with Rhodes using his wealth and power to extend British influence and ultimately naming a region — Rhodesia — after himself.