Genie smiled and asked "What's your next wish, my mistress?"
Jon looked at her, shocked that she would mess up his (or was it her now?) wish like this. Of course, Jon shouldn't have complained so much, since the wish he made with the wishing stone made it clear that the genie would twist the outcome of his wishes as much as possible. But he was still shocked, regardless. And his shock influenced his next wish.
"I don't want to be both black and white. I want to be one color."
Genie smiled and nodded. "As you wish, my mistress." She clasped her hands and a white cloud of smoke surrounded Jon.