Jon checked the time and saw that it was almost time to go. They'd be shooting the movie soon and he wanted to be sure he was there on time.
But before he left, he wondered if he should take his magic stone with him. He could just put it in his trailer when he got to the set, but he wasn't sure if it would be completely safe there. Of course, he supposed, he could make a wish to make sure it was safe, then he could take it with him.
"I wish that when this stone isn't with me, no one will try to take it without my permission." The stone glowed, granting his wish. Satisfied that his wish granted, he took the stone with him, not realizing that it wasn't really his stone.