Collectors Glossary

Below are lists of common terms collectors are likely to encounter in various categories.

Originally used for industrial purposes thanks to its ability to withstand heat, Bakelite was invented in 1907 by Leo Baekeland, and was one of several patented plastic resins (along with Plaskon, Beetle, and Catalin) that were popular in the 1920s and 30s. Associated with Art Deco style objects.

A piece of ceramic that has been fired but not glazed.

A design in relief that’s created when material is carved from the surface of shell or stone. Often used to refer to any relief depiction of a human head presented in profile.

A technique in which filaments of metal (often gold or copper) are soldered to a surface to create compartments that are then filled with ground enamel, fired, and polished.


An engraving technique that uses mechanical means to create precise, intricate, and repetitive patterns and designs, usually in metal.

Hard-paste porcelain: A type of porcelain that is fired hot at 1400 degrees Celsius to produce a hard, white, and translucent body.

The opposite of a cameo, an intaglio is achieved when a material such as stone is carved to produce a void in its surface. Often used in seals and signet rings.

A process developed in the 1850s in which pottery is covered with opaque enamel made from metal oxides, fired, painted, fired again, and then covered one more time in clear enamel.


Milk glass
An opaque glass, first made in Venice in the 16th century, that gets its rich white color from fluorite and tin dioxide.

A type of molding whose profile resembles an S-shape curve.

A variation of cloisonné in which enamel is framed by walls of fine wire or metal but not backed, allowing light to pass through the translucent enamel.

In an effort to make everything from radios to railroad trains look modern, designers streamlined their creations, producing a look that became ubiquitous during the heyday of Art Deco and during World War II.

A stone that has been shaped and polished instead of faceted. It usually has a flat back and a shape that is round or oval.

A plasticized form of nitrocellulose and camphor developed in 1868 to make billiard balls, which sparked when they collided due to the material’s flammability. Repurposed in the first half of the 20th century for use in costume jewelry.

Decorating a piece of metal on its surface, usually with hand tools that leave marks and make indentations but do not remove any of the surface material.

Another word for rhinestone.

Decorating a piece of metal on its surface, as described in chasing, but from the back of the piece. The resulting indentations are thus raised on the front. Also called repoussé.

En tremblant
A trembling effect on a piece of jewelry achieved by mounting coiled metal springs to the piece’s fitting. Brooches and other piece that have this effect are usually called tremblers.

When wire (usually gold or silver) is twisted into delicate patterns before being soldered into a larger frame.

Gold filled
A misnomer since the gold is actually visible on the surface. In the United States, the gold a customer sees must equal at least 1/20th the weight of the base metal below it in order for a product to be sold as gold filled.

Gold washed
An even thinner layer of gold over base metal than rolled gold.

Goldtone or gold-tone
A term used by costume-jewelry manufacturers and designers to describe their gold-plated or gold-washed pieces.

Fossilized coal found near Whitby, England. Used primarily in mourning jewelry.

Developed in the 1930s, this clear acrylic was less expensive to produce than Bakelite, Galalith, and Catalin and more chemically stable than celluloid.

A type of leaded glass that was invented by French jewel designer Georges Frédéric Strass in 1724. When cut and polished with metal powder, this precursor of the rhinestone appears to shimmer like a diamond. Also called “diamante” or “strass.”

A setting in which numerous small stones are set so tightly together that they create a uniform surface.

An alloy invented in 1720 by Christopher Pinchbeck, who discovered that a certain combination of copper and zinc resembled gold.

Rolled gold
Similar to gold filled, but with no weight requirement.

Gold-plated sterling silver.

A type of hardened rubber.

If a porcelain sign was not fired properly, the enamel will not bond tightly to the metal body. In such cases, moisture can fill in the gap, causing the enamel to craze in intricate networks of minute cracks, thus dulling the finish of the porcelain.

A flanged sign is folded at a right angle at one end so that the sign can be bolted or otherwise attached through the flange to a wall.

A watch that measures time intervals like a stopwatch.


A “complicated” watch is one that displays more than just hours, minutes, and seconds. Complications include annual calendars and time zones. So-called “grand” complications include moon phases, chronographs, and sky charts.


The ability to push a single button on a watch to stop, reset, or restart its chronograph function.

A cone-shaped piece in a mechanical clock or watch that is attached to a spring via a length of chain.

A unit of measure (2.256mm) designating the size of a watch movement.

Back to all questions »

Related Questions