Puzzle Quest: Galactrix - gem color chart

Red: Weapons—Collecting these will add to your weapons value.
Yellow: Engine—Collecting these will add to your engine value.
Green: CPU—Collecting these will add to your CPU value.
Blue: Shield—Collecting these will go towards recharging your shield value.
Purple: Psi—This is used outside of battle when interacting with NPCs.
Grey: Intel—Collecting these help get you better insight and you may even hear more rumors.
Black: Damage—The basic attack gems return, but with new values and variables.