Appearance and Material nodes control a shape's shading color (diffuseColor), glow color (emissiveColor), transparency, shininess, and ambient intensity.
Colors specify a mixture of red, green, and blue (RGB) light with component values between 0.0 (none) and 1.0 (lots).
ColorInterpolator can animate color values, and
ScalarInterpolator can animate transparency values.
These X3D scenes are adapted directly from the
original VRML 2.0 Sourcebook chapter examples.
Introduction to VRML97 SIGGRAPH98 course notes.