"What?" Sarah asked, not realizing that Jon was making a wish.
But before Jon could finish his wish, Sarah pulled the trigger and "vaporized" the wishing stone. Suddenly, the Reality Editor disappeared from her hands, since it was the stone that created it. Then Karyn gained back her original hair color and breast size. Across town, the branch that was changed color by Jon the previous day (as a demonstration of the stone's wishing ability) returned to its normal color. All wishes granted by the stone were systematically being taken back, as though they weren't wished in the first place.
But it didn't just stop with wishes made by Jon and Karyn. It continued with wishes made by Jon's grandfather and then to the previous owners and the owners before them, all the way back through time to the day the stone was created.
Sarah and Jon watched as their surroundings swirled around them like a technicolor whirlwind. And when it stopped and the world came back into focus, it wasn't the world they were used to. Because all of the stone's wishes were taken back, the world had completely changed. It was a world without the wishing stone.
The only thing left from the normal reality was Jon and Sarah's memories of it.