This question contains spoilers…
(view spoiler)[I'm really curious about the willstones, what they look like, what the inspiration was for them, and if we get to learn more about what magical ability those who bond with specific types may have? (hide spoiler)]
You are going to learn more about willstones in the second book--what the colors mean, how they are used, who bonds with which kind. I don't want to give too much away, but there is a communion between a person and his or her willstone--almost like another consciousness.