Use diffuse surface color:

Use diffuse and specular surface color:

Use glow color, setting the diffuse surface color to black:

Use Blend to mix two or more colors:

Use Lighter and Darker to mix with white and black respectively:

Select complementary colors, by selecting them maximally apart on the color wheel:

Color the filling according to the argument of a complex function:

Color the surface according to the argument of a complex function:

Plot the iso hue surfaces from the RGB cube. The hues are 0 (red), 1/6 (yellow), 2/6 (green), 3/6 (cyan), 4/6 (blue), and 5/6 (magenta). The primary colors are red at 0, green at 1/3, and blue at 2/3. The secondary colors are mixtures of two primary colors, so yellow at 1/6 is a mixture of equal parts red and green, etc.:

Manipulating the hue component interactively makes this easier to understand:

Plot the iso saturation surfaces from the RGB cube. The resulting iso surfaces are hexagonal cones, and the HSB color model is also known as the hexcone model:

Saturation for RGBColor[r,g,b] is given by (Max[r,g,b]-Min[r,g,b])/Max[r,g,b], so saturation 0 corresponds to the gray line, i.e. :

Saturation 1 corresponds (see above) to the surfaces , , or :

Manipulating the iso saturation surfaces makes it more intuitive:

Plot the iso brightness surfaces. The brightness for RGBColor[r,g,b] is given by Max[r,g,b], maximal output from any color channel:

Brightness 0 corresponds to black, i.e. RGBColor[0,0,0]:

Brightness 1 corresponds to the planes , , or :

Manipulating the iso brightness surfaces makes it more intuitive:

Plot iso chroma or colorfulness surfaces in the RGB cube. The chroma c for Hue[h,s,b] is given by c==s b, resulting in saturation sc/b:

Chroma for RGBColor[r,g,b] is the distance to the gray point with the same brightness. The resulting formula is Max[r,g,b]-Min[r,g,b], which can also be used to visualize the following:

Chroma 0, the achromatic colors, corresponds to the gray line :

Manipulating the iso chroma surfaces gives more intuition:

Combine the iso saturation and iso brightness surfaces and show that the intersection is a polygonal curve. The hue is the fraction of length around this polygonal curve in the counterclockwise direction as seen from the white RGB corner, i.e. , starting at red:

Iso saturation and iso brightness intersect at the hue curve, a polygonal curve with six vertices: