Looking for book I read when I was a kid

I’m looking for a fantasy book that I read in the early 2000s. The lead is a female in her early teens. I think she has red hair. I think part of the plot has her escaping a large wall surrounding the city. Not positive about that. I think the cover art is her holding a gem for one of the books in the series in a close up shot. I think she has pale skin. Any thoughts?

by Hour_Ad1064