Nobody mentioned this but I thought I should-the kits aren't very expensive, I think from DanceSafe its 50$ for a complete set. Totally worth it, imo, if you're not sure about your stuff. I was going to order a set but could not because of recent events in my personal life.
I had heard if you heat molly, if it leaves a black residue, its cut. I only say this as heating it would be reversing the crystallization process, reverting it back to a heavy oil, right? At least to a degree, I know some would be lost from the heat. Don't take my word for this btw, OP, I just added this as an aside out of curiosity.