Collectable Plastic Jewelry can be divided into three basic categories: Celluloid, Bakelite, and Lucite.
Celluloid is one of the earliest man made plastics that was widely used in making plastic jewelry. Jewelry made of celluloid dates roughly from 1900-1930. Celluloid has certain characteristics which differentiate it from other plastics. In general, pieces made from celluloid tend to be thin, light, somewhat brittle, sensitive to heat (they crack and craze), and early celluloid can be extremely flammable (do not ever test with a hot pin!). Celluloid is flexible. It can be bent, twisted, and molded. When placed briefly in hot water, early celluloid smells like camphor, while later cellulose acetate smells like vinegar. Celluloid jewelry should be stored carefully. Extremes of temperature, moisture, exposure to cosmetics or perfume, or lack of adequate ventilation can cause a celluloid piece to become "sick" and begin to discolor, crack, or even disintegrate. A "sick" piece is contagious, and should be placed in quarantine away from other pieces.
Bakelite was developed by Dr. Leo H. Baekeland, and it was patented in 1909. It was the first thermosetting phenol formaldehyde resin. Other companies produced similar phenolics, calling their products Catalin, Prystal, Marblette, and Durez, but since it is almost impossible to identify pieces by their manufacturers, phenolics in general are commonly referred to as Bakelite. A very wide range of items were produced from Bakelite, including billiard balls, telephones, radios, kitchen utensils, poker chips, and of course, jewelry. Bakelite's unique characteristic is that once it has been heated and formed, it can not be melted down and re-formed. It can be cast, laminated, inlaid, carved, and tinted almost any color of the rainbow. Bakelite colors, however, do change with age. Most pieces which collectors identify as Apple juice yellow were originally colorless, and white Bakelite mellows to a creamy ivory color. Bakelite can be transparent, translucent, or opaque. Bakelite tends to be heavy. When two pieces are tapped together they make a distinctive deep "clack", as opposed to the high pitched "click" of later plastics. Bakelite pieces develop a surface patina over time. Their surface color tends to darken, and very fine pits and scratches are produced with wear. A nice patina enhances the value of a piece. When placed briefly in hot water, most but not all Bakelite has a unique unforgettable carbolic acid smell. Bakelite should be stored carefully, although it is not as fragile as celluloid.
Lucite, an acrylic resin, was first marketed by DuPont in 1937. Lucite began to appear in costume jewelry around 1940. Like Bakelite, it is a thermoset plastic, but it was much cheaper to produce. Lucite could be molded, cast, laminated, inlaid, and carved. Although in its original state it is clear and colorless, it could be tinted any color of the rainbow, from transparent to opaque. Lucite continues to be used in jewelry manufacture, but it reached its height of popularity in the 1940s-1950s. Common post-war pieces of interest to collectors include clear Lucite imbedded with glitter, seashells, rhinestones, or flowers. When placed briefly in hot water, Lucite is odorless. Older Lucite can develop cracks from age or exposure to heat.