text: 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