Five light colors can be defined. The colors at the corners control their corresponding light sources, which are located in the corners of the texture. The middle color regulates the tint and intensity of the ambient light. 

Supply the relief data with the Source Texture or the Mask. Increasing the Pre-Smoothing parameter leads to a blurred heightmap.

Increase the light intensity with the Amplify value.

The Transformation is very important for the outcome of the operation. It manipulates the illumination gradient, which is dependent on the angle of the light source to the heightmap surface. E.g. for the gem in Image 3, the Noise Round transformation was applied to the illumination gradient.