This stone looked nearly the same, but it wasn't. It was the Multiplication Stone, a cursed item that did grant wishes, but the wishes were multiplied by an unspecified amount. For example, if the wisher wished to age by a year, they would in fact age by a random number of years.
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.
