Stoneware is a category of clay and a type of ceramic distinguished primarily by its firing and maturation . In essence, it is man-made stone. One widely recognized definition is from the Combined Nomenclature of the European Communities which states, Stoneware, which, though dense, impermeable and hard enough to resist scratching by a steel point, differs from porcelain because it is more opaque, and normally only partially vitrified. It may be vitreous or semi-vitreous. It is usually coloured grey or brownish because of impurities in the clay used for its manufacture, and is normally glazed.