Just about everybody who has been married has invested in the blood diamond trade.
The DeBeers trust supposedly avoids them because they undercut diamond prices that DeBeers can get.
A hint: neither South Africa nor Russia produces them.
There would be very little market for diamonds, blood or otherwise, if not for the insistence of people on the silly diamond tradition. There are some industrial uses here and there, but most diamonds go to brides who will probably end up fat and divorced in a few years time anyway.
The industrial uses are largely supplied by artificial diamonds these days. Making diamonds for use as abrasives is less costly than getting them out of the ground, so only the rejects from mining for gem-quality stones make it into the industrial supply. (Much as a good deal of the silver mined these days is recovered as a byproduct of mining for lead or copper.)