A synthetic substance that, being susceptible of being moulded by heat and pressure, is used for many modern purposes, including making articles of costume jewelry and junk jewelry. Plastics can bemanufactured in many varieties and in infinite colours and can be given a metallic appearance, and also can be treated by electroplating. The material is light in weight, soft, and sectile. It can bemade to resemble any type of gemstone, and also certain natural substances, e.g. amber, coral, ivory, jet, and tortoise shell, but they are readily distinguishable by the resinous lustre, internalbubbles, low degree of hardness, rounded edges, etc., of plastic.Plastics are made of varying components, the most common varieties being celluloid and nylon. Vinyl plastics and acrylic plastics are sometimes used in jewelry to imitate gemstones and also as thenucleus for an imitation pearl.