I've done my fair share of coke, but the only time I can say without doubt it was pure was the time I had a gram of peruvian black. Every bag I would buy, presumably from the same dealer, was decent. Perfect for a junkie because it was in-expensive, but not low quality, really aimed at those who will give their whole check to the damn guy, you know... Anyways, one day, and it was never again, he busted out a bag of blackish looking cocaine (More like glassly with black tint) I was like wtf is this, man? He charged me 60$/G (really high considering I'd get the Ball for $120), and man-o-man was it YAYO. I don't pretend to know %'s, just that I know if it's good or not. This was probably 95%+ and since I have never even come close to that quality.