Crystals (Spoilers)

OK you know in the game that when an enemy dies they either drop a crystal or a treasure chest. Most players know this. But did you know about the different types of crystals? There are blue, which restore Hp/Mp only, yellow which either restore Hp/Mp or you can learn an ability from. Then there are these purple crystals. I have only seen non human enimies drop them, yet I have no idea what there purpose is. I wonder if MAYBE you can learn monster skills from them but have never tried it out. Dose anybody have any clue?

You can't learn monster skills from crystals. I think we've been over this already.