Nobody seemed to notice anything strange about Jon during gym so far. Of course, the only visible difference was the lack of a bulge, but someone would have to have noticed it anyway, right?
No, wait, thought Jon. Nobody should think that he suddenly changed. That's how the wishes worked--the thing that has been wished for becomes part of reality. People think it was like that all along. The note from Jon's grandfather had explained exactly how the stones worked. The real stone, that was willed to Jon, grants wishes that alter reality; the fake stone, that was willed to Zoe, did exactly the same thing except Zoe had to interpret the wishes first.
He didn't realize it, of course, but once Zoe wished for a fake stone that worked in a certain way, reality changed so that for her to have such a stone was part of reality--complete with grandfather's note telling Jon that he was willing the fake stone to Zoe.
It didn't yet occur to Jon that he had the wrong stone, but in the new reality he knew that the wrong stone existed, so he could figure it out sooner or later....
