It's a crystal, nothing more.

We go to the Renaissance Festival in Shakopee, MN every year. This year I actually remembered to wear my finger armor. There was a stall selling clear and colored glass balls. I took this picture at the beginning of the day, since the stall is near the entrance/exit.

When we were on the way out, I decided to buy two of them. I wanted at least three but I only had enough money left for two.