17. Continue loading each Channel Mask as a selection and filling each one in turn with progressively darker colors until you are done.
You can change hue as well as value, starting with light pink, for instance, and ending with dark blue-violet.
Experiment! Try reapplying an earlier mask if you wish and change the colors. Instead of adding new color, use the Levels or the Hue/Saturation dialog boxes. Adjust the overall color using the Color Balance or the Hue/Saturation dialog boxes. Just for fun, try starting with dark colors and working towards white.
I usually finish off by adding a little Noise to give the marble some stone texture. Don't overdo it, though; marble is smooth.