Costume jewelry is often made from gemstones which resemble precious stones or from imitation stones which follow certain periodic fashion trends. Developed in the 18th century, mainly for the emerging middle class and the wealthy who, who wore valueless jewelry for security while traveling. In the 1920s costume jewelry developed into an accessory in it’s own right rather than an imitation. It then became ostentatious in the hands of popular designers such as Chanel and Schiaparelli. Various materials are often used and painted imitations of silver and gold, as well as resins and other plastics which mimicked the precious stones. Costume jewelry is now an integral part of the fashion scene. Often commanded for exceptional designs.
Source: The Thames and Hudson Dictionary of Fashion and Fashion Designers