Cullinan is a small town in the Gauteng province of South Africa. It is located 30 km east of the city of Pretoria along the diamond route an…Cullinan is a small town in the Gauteng province of South Africa. It is located 30 km east of the city of Pretoria along the diamond route and is heavily reliant on tourism and the mine that dominates the skyline. The town is named after diamond magnate Sir Thomas Cullinan.