The person who grabbed for the stone was Sarah McMillan.
When Jon was showing the stone to Karyn the previous day, Sarah was spying on them. She saw that the stone could grant wishes and she was devising a way to take it from that loser Jon and his friend Karyn. But, it seemed, that she didn't need to do any plotting, afterall. Jon's wishing stone was sitting on her nightstand. She didn't know how it got there, but she was happy that she got it.
She held it in her hand and thought of something to wish for.
She smiled when she thought of something. "I wish ..." she said, not realizing that her wish would be granted to Jon, instead of her.
