a simple view of odds of success...

I'm posting this because other posters have stated that MK is 99% sure he'll find a commercial diamond source - I don't know if he ever said it, I doubt he did....

just for interest, here's a model of the general structure of a Kimberlite pipe. Quite accessible with depths usually 2.5km at most, even though the diamonds they rarely contain are formed at far greater and totally inaccessible depths. Contained diamonds are thought to bubble up through the molten pipes in a floatation process due to carbon dioxide absorption by the parent rock. Anyway, enough of that.

ok, here's an extract from an authoritative source (not wiki) on diamond pipe occurrence.