This thread is stupid. Color doesn't mean anything, sure "pure" mdma won't be brown or purple, but you are talking a difference of less than 1%...and I highly doubt anyone on earth could reliably tell the difference between 90% and 98% pure mdma by dosing, let alone 98% to 99%. Set, setting, diet, mental state, how much sleep you've been getting, history of use, etc. etc. are going to have a MUCH larger affect on your roll than the difference of a couple milligrams in your dose. Hell, just pharmacokinetics are going to mean your effective dose and peak are different session to session more than the purity of your mdma.
edit: just saw how old this thread is...and this isn't the first thread you've necroed, Rhythmicraven, please don't necro old threads for no good reason