How do you determine what the tone quality of a singer's voice should be?
A singer's tone should be determined by his or her own individual vocal anatomy and not a predetermined ideal held by a teacher – or the student, for that matter! It should be a blend of the top, middle, and bottom resonance qualities that results when the singer's larynx remains in a relaxed, stable position.
What about breathing? Doesn't correct breathing play an important part in your ability to produce good tone?