During the Depression Era, commonly thought of as the day the Stock Market crashed in 1929 until the start of WWII, glass companies in the United States began experimenting with color.  Colored glass had been introduced prior to this but it was during the Depression years that the production of it was in its heyday.  Companies such as Heisey, Cambridge, Fostoria, U.S. Glass, New Martinsville, Paden City, etc produced some of the prettiest pieces of bedroom and bathroom glass you'll ever see.  The items they produced included powder jars, perfume bottles and atomizers, lamps, vanity sets, towel bars, and the list goes on.  Colors ranged from pink and green to black and red and everything in between.  Some of the pieces have very classic traditional shapes and others are pure Art Deco.   Fired-on color is color that was sprayed onto the glass after it was molded and then it was re-fired.