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.

Among the most collectible forms of plastic jewelry from this period are those that reflect bereavement. In England mourning jewelry was mostly carved from jet, but as jet supplies began to dwindle, alternative materials were sought to replace it. Hardened rubber, gutta percha, shellac and dyed horn were all natural plastics with excellent molding properties. By the late 1860s, all of these substances were being used as alternatives for jet.

Hardened rubber was first patented in America in 1839 by Charles Goodyear. He discovered that by treating natural elastic rubber from the Hevea tree with sulfur and heat, it became hard and durable. In 1844, Thomas Hancock of England also patented a similar process called vulcanization. The result was vulcanite, named after Vulcan, the mythical Roman God of fire and brimstone. By 1860, ebonite joined the ranks of hardened rubber and within five years, the manufacture of hardened rubber jewelry was in full swing.

Composition plastics were also used in jewelry and small personal accessories during the years surrounding the Civil War in America. Shellac, which found its greatest application in daguerreotype cases, had excellent molding properties, making it suitable for use in ornate brooches, lockets and buckles. Shellac was a combination of wood flour, carbon and lac, the excretion from the lac beetle, which was harvested from the bark and twigs of certain trees in Asia where the insects thrive.

Lac was refined by melting and pouring the material into large sheets which hardened and were then ground into flake form.

Horn and tortoiseshell were both natural plastics derived from the animal kingdom. Made up of protein called keratin, they were easily manipulated by heat and pressure and so found a myriad of applications in jewelry, ornamental hair combs and small accessories.

Horn came in an array of light and dark variations that made it suitable for many uses. It could be machined, cut and carved, molded by heat and pressure and also clarified by pressing, making it translucent. Horn is easily identified by observation. Its structure resembles compacted hair and, as it ages, horn frequently frays or peels apart in tiny, thin sheets.

Tortoiseshell comes from the Hawksbill turtle, a marine species that now faces extinction due to over harvesting. This natural plastic is beautiful, with mottled streaks of amber, orange and deep shades of brown. Mottled shell was mostly used for ornamental hair combs, but hatpins, brooches, lockets, chatelaines and other fancy small goods were fashioned from this lovely material as well.

Tortoiseshell had properties that made it easier to work with than horn, which often frayed or splintered during fabrication. One of its virtues was the ability to fuse pieces together using heat and pressure. This made tortoiseshell scrap recyclable. One interesting characteristic of tortoise shell was that it darkened with repeated applications of heat, so it was suitable for use in mourning jewelry.

Since horn and tortoiseshell are natural protein plastics, they are susceptible to infestation by a microscopic parasite that lives off it. If a piece exhibits tiny chipped areas or what appears to be surface pitting or tiny holes, it is most likely being slowly consumed by these natural predators. There is no known way to prevent this form of deterioration.

In 1869 the first semi-synthetic plastic material was invented in America by John Wesley Hyatt. Called celluloid, by 1875 it was successfully being used to imitate a great many expensive luxury materials. Made in convincing imitation of elephant ivory, amber, coral, jet and tortoiseshell, this early plastic afforded working-class women the opportunity to enjoy beautiful, authentic looking jewelry at an affordable price.

In dating celluloid jewelry take note that, prior to World War I, celluloid was primarily made to imitate natural materials like tortoiseshell and ivory. After the war, color became all the rage and celluloid jewelry took on a new look. It was laminated in contrasting layers of color, painted with silhouettes, studded with rhinestones and made to resemble mother-of-pearl. Glitz was en vogue then and still is today. Collectors will pay anywhere from $50 to $100 or more for brooches, bracelets and pendants made from this material.

Bakelite is perhaps the most widely recognized plastic used in jewelry. It was developed between 1907 and 1909 by Dr. Leo Baekland, and was the first true synthetic plastic. Originally it was formulated as a dark molding compound used only in industrial applications, but in 1927, the American Catalin Co. developed a purified form of the plastic in 20 different colors. This opened a brilliant door of opportunity for the manufacturers of jewelry and, by 1936, two-thirds of all costume jewelry made in the United States was fashioned from Catalin and Bakelite. Bangle bracelets, brooches, dress clips, rings, pendants and buttons made from this material can be found in an array of translucent and opaque colors.

Bakelite and Catalin jewelry is clunky, thick and often heavily carved. Since it was very time-consuming and expensive to make, the heyday of manufacture only lasted about a decade. Today this jewelry is becoming increasingly scarce and expensive as collectors snatch it up. Ornate reverse-carved bracelets and brooches with dangling components can sell for $350 or more.

Acrylic, also called Lucite, is another 20th century plastic that has captured the attention of collectors. It was first introduced in 1936 and found its way into jewelry by the 1940s. The pure, translucent quality of this material made it suitable for faceting, reverse-carving and casting with tiny objects suspended in the plastic.

Lucite was also studded with rhinestones and layer cast in colors for special effects. One of the most collectible forms of jewelry with acrylic components is the "jelly belly." Jelly bellies are brooches or pendants that have the shape of an animal crafted in metal, with the center – or belly – made of translucent plastic.

One of today''''s most widely recognized names in modern 20th century plastic jewelry is Lea Stein of Paris. Stein began fashioning jewelry from Italian laminated cellulose acetate with the help of her husband, Ferdinand, in 1954. Among her famous multidimensional brooch designs are Art Deco women, stylized foxes, turtles and a host of other objects. By 1980, high production costs put Stein out of business, but in 1991, she resumed designing and has since released two commemorative pieces a year. Stein''''s innovative use of color and artistic design make this jewelry so appealing that many have tried to copy her work. Look for authentic pieces bearing the trademark Lea Stein – Paris on metal findings. For an indepth look at Lea Stein jewelry, check out www.frenchbijoux.com.

Julie P. Robinson is a plastics historian and author of two books on the subject of celluloid. She lives in the Adirondack Mountains of upstate New York and may be reached by e-mail at: celuloid@frontiernet.net.