Glass coloring and color marking may be obtained in several ways.
# by the addition of coloring ions,
# by precipitation of nanometer-sized colloids (so-called striking glasses such as "gold ruby" or red "selenium ruby"),  
#by colored inclusions (as in milk glass and smoked glass)
#by light scattering (as in phase separated glass)
#by dichroic coatings (see dichroic glass), or
#by colored coatings