Complex sentence: The Premier Mine is an underground diamond mine owned by De Beers that is situated in the town of Cullinan, 40 kilometers east of Pretoria, Gauteng Province, South Africa.
Split into simpler sentences: The Premier Mine is an underground diamond mine owned by De Beers. It is situated in the town of Cullinan, 40 kilometres east of Pretoria, Gauteng Province, South Africa.