Hmm, actually, they aren't perfectly fungible. 100 one-carat diamonds aren't worth the same as one 100-carat diamond, and even diamonds of the same weight aren't substitutable. But with respect to country of origin, yeah.
Canadian ice diamonds, on the other hand, are all laser-engraved with a serial number, making it possible to verify each diamond's authenticity and source. According to the jeweller I spoke to, the only guarantee she could make is 'Canadian' or 'not Canadian'; she couldn't even guarantee me African, Russian, etc.
She did, of course, offer to sell me a ring with 'who knows' diamonds and then remove them and put Canadian diamonds in, but at that point I'm paying for 'who knows' and Canadian diamonds, which seemed a little idiotic.
Because Africa is all one big war zone. Because any money sent to Africa funds violence.
Seriously? Why is it so much better to buy from Russia than South Africa or Botswana? (the money's all going to De Beers -- which was originally a South African company -- or a similar multinational anyway).
The top four diamond-producing countries in Africa (the top two are actually not African: Russia and Canada) are Botswana, Angola, South Africa and Namibia. All of these countries are poor, sure. They all have some political problems, sure. But they are all democracies with somewhat functional governments; none of them are at war (the Angolan civil war ended in 2002).
Multinational mineral companies aren't always the best thing for locals, but the idea that the only money sent to Africa should arrive on a UN food truck is far worse.