Cole could not be convinced to use his diamond ranked prism, he was also out of gold ranked prisms and only had two silver prisms left along with the iron grade he just received.
But then again there might be no reason to use them, he was stuck in a tough place because he wasn't exactly sure if he would use the prisms along with the stat Points he had available to try and push the rest of his stats to the Iron Rank. Since he has accepted all of these bounties, he might be facing things way above his current ability, and while his weapons gave him a whole other level of power, Cole really wanted to be absolutely careful.
So he used two silver prisms and one iron rank prism. Depending on what he gets, he would allocate the stat Points available to his stats and see just which one could be pushed into the Iron rank as soon as possible. After all there was a massive stat bonus and boosts to be received when all stats cross the iron threshold.
