To me, "apartheid South African emerald mine owner" appears to mean that the mine was in South Africa. It does have a bit of ambiguity. I think that it's important to provide enough detail to make the scope of exploitation involved clear. Sometimes it can be simple, like "sweatshop" but, in this case, Musk has invested a lot of energy into his myth of a "self-made" man, especially in suppression of the origins of his wealth that it behooves use of done specificity to demonstrate how rotten even his origins were.