The stone he put in its place looked almost exactly like Jon's stone, except that it wasn't. It was The Love Stone.
It worked just like the normal stone, except that after a "hateful" wish is made towards someone, the wisher falls in love with the target of that wish ... and then would make additional wishes to help that person instead of harm them, regardless of how they felt about the person before they made the initial "hateful" wish.
The wisher won't think that it's strange that he or she is in love with the target of the initial "hateful" wish. But everyone else will think that it's strange, whether they heard the wish spoken or not.
