The Oppenheimers have been in the diamond industry for about 100 years.

BBC: Rough diamond held between tweezers

Botswana also has a pre-emption right over the Oppenheimers' shares, so it may yet increase its stake in De Beers from 15% to 25%.

ECONOMIST: Diamonds

For all the 16 years that we and our sister publication Forbes have been putting out these lists, only two private fortunes from that land have appeared: those of the Oppenheimers and the Ruperts (of Richemont-Cartier note).

FORBES: Sidelines