Jon waited for the glow of the stone, but nothing happened.
"Great!" Jon said sarcasticly. "Now I have a useless stone stuck to my hand!"
Then a thought occured to him: They have the power of the wishing stone. He looked at his surroundings and at himself. Things could be different and he wouldn't know it, if they used the stone.
He had to get it back to minimize the damage they could cause to the world.