Jon waited for the stone to glow, but it didn't. Puzzled, Jon made another wish. "I wish I knew why my last wish didn't get granted." The stone glowed, granting that wish. "Oh." Apparently, what he had wished was already true. Just because every intricacy of the object wasn't spelled out in the instructions didn't mean that the make-up worked on babies and young children. In fact, the make-up only affected people who had hit puberty.
He put down the stone and picked up the Make-up of the Goddess again, wondering once more whether he should use it on himself or someone else.