A very good place to start on your tone is watching Ken's Stage One video. He shows you exactly how to create a bright, timbral sound with the Open Throat. There are a number of factors such as posture, jaw position, tongue placement, etc. that factor together in combination to affect your tonal quality.
Good cord closure is also of high importance in vocal tone.
Vocal Cord Adduction.
If the cords are not closed together, or properly "adducted",the result will be an airy, weak, dull sound. Too much air is the enemy of the voice, and dries out the vocal cords.
Proper cord closure results in brighter, richer tone.