Nice article that explores the multitude of materials that are and were used to make jewellery:
Antique Week – News Article
By Julie P. Robinson
November 3, 2006
“Many people assume that antique and collectible jewelry must be fashioned from precious metal or gemstones in order to be valuable, but this is not true. Many types of plastic materials were used to fashion jewelry beginning in the mid-1800s. Today, items made from these materials are widely collected for their rarity as well as their intrinsic beauty.
The word plastic technically means any substance that can be made pliable for molding. Natural plant and animal plastics, like rubber and tortoiseshell, as well as composition materials like shellac were all used to mold beautiful jewelry objects.”