Maker - Alchemy Skill FAQ and Walkthrough

Black Crystal: Random [1, 2, 3]
Dark Crystal: Random [2, 3, 5]

UHM... I think I have a theory for these ones. Maybe the black crystal can only add a random stat from any regular jewel (attack, speed, hp, etc...), while the dark crystal can only add from any crystal (STR, INT, DEX, LUK).

Kinda makes sense, but I obviously don't know the real deal :p