Red fire commands the highest price, especially if it shows brightly from a dark gray base. Blues, greens and lavenders are of lesser value. Ideally, the rough will display a combination of red and green or blue fire. The base color of the quartzite matrix will affect the value as well.
Dark gray is the best followed by light gray, cinnamon brown and white.
There is a grade of white that displays a fine grained texture and multicolored pinfire. If you haven't read the Rock Net FAQ and User Tips yet, now would be a good time to do so.