This stone looked nearly the same, but it wasn't. It was the Gender Reversed Stone. Any wish made with it that was gendered gave an opposite gender effect. For example, wishing for large breasts would give a girl manly pecs.
Jessica walked towards the spot where she usually met up with her friends before school. And as she approached Lucy Corinth (her ditzy friend), she took out the stone, completely unaware that it wasn't the same stone she inherited from her grandfather.
