Inlay material is a type of decorative art used to enhance the look of an object. Two popular materials used for inlay are NACRE (5 letters) and niello (6 letters). NACRE, also known as mother-of-pearl, is a type of organic-inorganic composite material made from calcium carbonate and conchiolin. It is often used to make jewelry and other decorative items. Niello is an alloy of copper, silver, and lead that is used to create black or gray designs on metal surfaces. It is often used to decorate jewelry, weapons, and other metal objects.