Whenever you’re buying, selling, or appraising antique or vintage jewelry, you first need to determine what material the piece is made of. This can be a challenge because lookalike materials can easily fool the untrained eye. Here’s help.

They paid what? Collectors pay large sums for what used to be called “secondary jewelry.” Auction prices for antique and vintage items – earrings, necklaces, brooches, tiaras, lockets, hair combs, chatelaine elements, stick pins, hat pins – often seem high. It may be hard to believe, for example, that a collector will pay $1,500 for a plastic bangle, $250 for a peat brooch, or $385 for a rubber locket. But it happens all the time.

To understand why, remember that the value of these items is based not on the worth of the materials but rather on the workmanship. A chunk of Bakelite, a plastic patented in 1909, is not in itself valuable. But when it’s a finished item carved with an intricate design and executed in a bright color, the value skyrockets. Nostalgia, whimsy, provenance, demand, rarity – all of these factors can boost the price of antique and vintage jewelry. The very fact that an item resembles a piece worn by a famous person can enhance its value.

Victorian jewelry is popular among today’s collectors. This includes hair jewelry and mourning pieces made of jet, vulcanite, and bog oak. Sometimes you’ll find mourning pieces with imitation materials of glass, Bakelite, and the newer plastics.

As with any previously owned items, beware of myths and family stories. What Grandmom believed to be jet may actually be glass. Her “cherry amber” beads could be Bakelite. Family members may not know for sure when and where an item was bought. Grandmom may still have been shopping and receiving gifts well into her later years, which means some of her items may not be old at all. Obtain information from your client, but be sure to check out the identification and age for yourself.

What to look for. When inspecting the material, note the following:

• Mold lines. These are telltale signs of a machine-made piece.

• Color. Evenly distributed color usually signifies a synthetic or simulant.

• Pattern. A randomly distributed pattern generally indicates a natural product. A regular and repeating pattern usually means it’s synthetic.

• Hallmarks. Hallmarks that can help identify the material include signatures, patent or design numbers, the manufacturer’s name, the metal content, and the country of origin.

• Findings. Are they original? Are they “right” for the piece? Certain findings are associated with specific materials.

• Temperature. Jewelry materials can be classified as cold, cool, or warm. This can help identify the material.

• Weight. The weight can be deemed heavy, medium, or light, another way of determining what the piece is made of.

• Sound. Each material has its own resonance or sound that you can learn to identify. Tap the material with a fingernail. Or, if you have two identical items or two elements from the same necklace, tap them together to get the sound.

• Odor. Some materials have no odor, a few naturally emit a smell, and others give off an odor when warmed. You can learn to recognize these different smells. To produce an odor, rub the item briskly with your thumb. If you get no smell, dip it in hot water. Dip quickly and dry the piece immediately, as the heat can warp some materials. Don’t dip a piece with rhinestones in hot water, as the heat may loosen the stones.
  Materials and their characteristics. Here are the distinguishing characteristics of some of the materials commonly seen in antique and vintage jewelry:

• Bakelite. This colorful plastic was especially popular in the 1930s and ’40s. A warm and heavy material, Bakelite can appear opaque or transparent. It’s typically carved. Two pieces tapped together make a “clunking” sound. The material emits a distinctive odor when warmed.

• Bog oak. This fossilized peat from 19th-century Ireland has a matte brownish-black finish. Warm and lightweight, the material can be either press-molded or carved. You’ll often see it in pieces with Irish motifs, such as shamrocks, harps, and castles. Bog oak leaves a brown streak when rubbed on a white, unglazed tile.

• Celluloid. Cellulose treated with nitric acid and camphor can appear in many different colors. It’s warm, lightweight, and flammable, and it smells like camphor when warmed.

• Cellulose acetate. Cellulose treated with acetic acid typically appears in bright colors. It too is warm and lightweight. It smells sour when warmed.

• Jet. This fossilized coal, which comes mostly from Whitby, England, was popular from the 1850s to the 1880s. It’s usually shiny black, occasionally matte. Warm and very lightweight, jet is invariably hand-carved, so no two pieces are identical. It leaves a brown streak when rubbed on a white, unglazed tile.

• Lucite. Introduced in 1937, Lucite is DuPont’s trade name for acrylic. This medium-weight material can be either colorless or tinted with many colors. It emits a fruity smell when dipped in hot water.

• Vulcanite. This rubber material treated with heat and sulfur was popular in the 19th century. It’s molded rather than carved, so you may encounter identical pieces. It leaves a brown streak when rubbed on a white unglazed tile and smells like rubber when warmed. Don’t dip it in hot water, though, as the sulfur will migrate to the surface and discolor the piece.

These guidelines and criteria generally can make it easier to identify the material used in antique and vintage jewelry. No longer will you need to turn away your customers’ “mystery pieces.”

Sheryl Gross Shatz, a Certified Gemologist who teaches at Santiago Canyon College in Orange, Calif., is the author of What’s It Made Of? A Jewelry Materials Identification Guide. All photos from Warman’s Jewelry, 2nd ed., by Christie Romero.