So, what your link says is that the gem restriction only applies to gems used for fatigue. The cost can be paid by any mage of any power (assuming they can cast the spell in the first place).
Ok. But then how do you explain the fatigue of the caster? If the above information is correct he could have used 5 gems (aside from the costs of the spell) to break down the 500 fatigue of the spell easily.
RonD, I dont think you are correct. I've talked to several experienced players and they assure me that the gem cost is taken from the max amount of gems a mage can use.
Hmm, I was hoping someone would have a solid answer but it looks like I am going to have to test it