Everyone else has already suggested my first thoughts.
I just wanted to add a wild-card option:
Emerald, nn
Merle.
I was over at babynamegenie.com the other day. A parent to be was asking what others thought about
Emerald as a name. Loving it, I clicked on that thread. Someone else responded with
Merle as a nickname which I thought was kind of brilliant. It means "blackbird" which is neat in and of itself. But it could work really well for your character. It sort of sounds like
Merlin. And
Emerald has a magical quality to it, at least to my ears. Make those green eyes and you may be on to something. Good luck! :0)