can crystals oxidize or go bad if left exposed air for a few weeks?

if they can oxidize what would happen to them?

Yes, they will lose potency. If left in open air and bright light, expect to lose it fast.

In my limited experience, oxidized spice leaves nothing to be happy about. I experienced a heavy, uncomfortable weight in my head, no visuals, and a definite need to say "aww, bummer dude."

I have heard of a way to "fix" oxidized spice, but I haven't a clue on whether or not it's myth or fact. Hope that helps.

would it change in appearence?

In SWIM's experience, no, it will most likely look the same.

Cosine with Leap, SWIM's felt the exact same way before

I've had synthetic DMT go from pure white to slightly yellow over the course of a year, kept at room temperature in tinfoil. No noticeable loss in potency though and it can be purified of the oxidized spice by recrystallization.

yes oxidized DMT is certainly active.

Many month old DMT has been smoked and has been effective.

People cary loads of the stuff at festivals and such all summer and have no problem with it.