Yes a texture or ramp would be a good solution for this.

I can help you a bit with the nurbs tessellation however, the method you use depends on the render engine you use. I use mental ray to render nurbs because it has the approximation editor which greatly simplifies the process of optimizing tessellation at render time.

Once again it much more time efficient for me to make a video then try and type out an explanation and grab screen shots...

So bare with me as I whip a video up for you...