Diffuse B
The Diffuse group applies to the currently selected surface in the surface combo box below the preview.
Color sets the base diffuse color of the surface.
This setting has no function in conjuction with Surface 2.
Scales the Diffuse Color to produce attenuation in the illumination of the surface (this simply means it makes the color darker when the value is close to zero and brighter when the value is closer to 100% or above). If you are utilizing the Oren Nayar illumination algorithm you may want to bump up the illumination about 10% to 20% because it renders darker usually. Appropriate values are between 0% and 200%.
Provides contrast for the result of the diffuse sample color. Zero causes no effect, 0.0% - 100% causes standard contrast, above 100% causes a wrap contrast (the values that go above 100% wrap around to 0% again, used to create the Candy materials), negative values provide an inverse contrast that simulates materials that seem luminescent, such as silver. Appropriate values are 500% to 500%.