There's a book that I'm dying to find, only I can't remember many of the details. I don't know the name or the author, who it was published by, or really the storyline. It's fiction, fantasy if I were to put it in a category. I know the main character is a girl, and she has two best male friends, one has a lopsided grin. She goes to a school for music with these two boys and other children of all ages (on an island?). One of her male friends loses his singing voice, and has the choice between leaving, and staying on as a servant/janitor type person. There's also something about a blue stone in it. The cover shows the main girl holding a blue stone, with landscape in the background. The cover isn't a picture, it's an illustration. Also, it's a teen book. Please help me! I've been searching for this book for 5+ years.