The origin of enameling can be traced to ancient times when vitreous (made from glass) enamels were used on and in metalwork. This practice reportedly enabled the artist to use glass in place of rare gemstones--for example, cobalt glass in place of lapis lazuli and a reddish/brown color for garnets. Modern day vitreous enamels can still be found in these original colors along with many others, expanding the artist's palette.
Enamels are fine particles of glass applied to metal to add color. Enamels are typically applied by dry sifting the particles onto the surface or by wet packing the enamels into channels or depressions in the metal. Once applied, enamels are heated until they soften and flow; the heat source used is a kiln or torch. The mineral composition of each enamel effects how the glass reacts in the heat and how it reacts on the metal.