Emerald Jewelry JarPorcelain, hand thrown, jewelry jar with an emerald green crystalline glaze. After the glaze fire I etch each piece in sodium bisulfate for 24 hours, lightening the background (even turning it white in some areas). Every piece is thrown and trimmed on the wheel using Coleman porcelain. This jar was fired in an oxidation atmosphere in an electric kiln. Crystal glazes are fired to cone 10 (2350 F) until they turn molten and begin to run down the surface