This stone looked nearly the same, but it wasn't. It was the Donut Stone. And because of its bloated doughnut shape, all wishes made with it would be granted to everyone 50 feet around the person who made the wish (as if they had made the wish themselves), but not the wisher or anyone who heard the wish made.
Zoe walked towards the spot where she usually met up with her friends before school. And as she approached Athena, she took out the stone, completely unaware that it wasn't the same stone she inherited from her grandfather.