This is what I remember-
A teenage boy walking in the local mall. He sees a necklace hanging on a jewelry cart, I think it was green and square, but it appeared to be glowing. He just had to get it. While he was walking home, he was slightly paranoid because of all the crows. I think the necklace was intended to be a Christmas present, but he ends up smashing it with a hammer. I think it was a smaller stone inside. He finds more of these, I think there are seven or eight.
If more information is provided I should be able to remember if its in the story line, thanks.