After blowing a half oz in a week, mainly to myself... I learned the trick.
Everyone swear they have bomb.
The only true way to know, it's to purify a set amound and then weigh final product to get an estimate %.
With that being said, instead of going to the guy charging $100/g for some 35% he thinks is 90..
Go to the guy charging $100/8 ball because he knows its 25%.
Buy bulk for less. Purify. Bingo. more blow less money. Look up the ethanol wash. It's an improvement on the acetone wash with simpler instructions and much faster.