It’s the late 1990s and rebel armies in Angola, Sierra Leone and Congo are bankrolling campaigns of mass murder and terror with diamonds. Now, after years of turning a blind eye, the diamond-buying public is starting to notice the bloodshed. But as the issue of so-called “blood diamonds” rises up the political agenda, De Beers is plotting what might be the boldest move yet in its long history: giving up its quest to control all the world’s diamonds.