Jewelry and Gemstone Glossary of Terms

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Palmwood

The characteristic spotted look of palmwood is from the rod like structures found within the grain of the original wood. Depending upon the angle the lapidary uses to cut the stone, these structures show up as spots, tapering rods, or lines.

Petrified palm wood is very hard, a 7.5 on the Mohs scale and ranges in color from black, light beige, yellowish-brown and brown.

Patina

The surface coloration of metal due to natural oxidation, age, wear, or the application of chemicals and/or acids. Brass, copper and bronze often acquire a green patina, silver turns gray or black and gold acquires a reddish hue.

Jewelers often apply a combination of various chemicals and/or acids to metals to enhance the design.

The term used to describe the surface of a gemstone which exhibits a luster similar to that of a pearl or mica.

Pennyweight

A measure used to weigh precious metals of gold, platinum and silver, a pennyweight (abbreviated dwt.) is equal to 24 grains and there are 20 pennyweights in a Troy ounce.

Petrified Wood

Petrified wood is wood that has fossilized leaving a stone like replica of the original wood. Petrified wood is also called Xyloid jasper or jasperized wood. Palmwood is a specific type of fossilized wood from ancient palm trees characterized by dark spots.

Pewter

Pewter is an alloy of tin, lead, antimony, and a bit of silver or copper. Pewter was the most widely used metal in America between the early 1700 and 1800's. The best pewter is achieved using a low lead content and a high tin content. As you would expect, U.S. pewter manufacturer's today are required to make lead free pewter. Both copper and antimony are added to the tin to make a harder metal alloy.

See alloy.

Pin / Pendant

A piece of jewelry that may be worn as either a pin or brooch or as a pendant. Sometimes this is accomplished by slipping a small tube with an attached bail over the pin stem when the piece is to be worn as a pendant. In other cases, the bail is hidden on the back of the piece just above where the pin stem is located.

Platinum

Platinum is the rarest of the three precious metals (platinum, gold and silver). It is harder than gold or silver making it more durable for jewelry purposes. It has a whiter color than silver and is resistant to oxidation (tarnish). Challenging to work with due to its high melting point it is difficult to alloy and cast. Platinum was discovered in the 1700's in Russia and is abbreviated Pt. or Plat.

Plique-a-jour

Plique-a-jour is an enameling technique in which transparent enamel is fired in cloisonné, (similar to wirework filigree), so that light will show through. An effect similar to stained glass windows, it is used in jewelry, bowls, vases and other art objects. Also, see enamel and cloisonné.

Potch

This term is used to describe common opal that has no value. It may exhibit slight color flashes but has no play of color.

Precious Gemstone

Diamond, ruby, sapphire, emerald and precious opal were once known as the precious gemstones. Other rocks and minerals used in jewelry were referred to as semiprecious stones or just rocks. Many people outside of the jewelry and gemstone industries still use these terms to differentiate between the stones.

However, there has been a great debate among jewelers and gemologists for many many years. The debate revolves around the term "semi" and whether an ugly, flawed emerald or sapphire is actually more precious than a beautiful tourmaline, amber or lapis lazuli.

The reasoning behind this debate is that the individual stone itself is the designator and calling a stone "semi" precious is a misnomer. Therefore, in recent years gemologists and jewelers have applied the term "gem" or "gemstone" to stones used in jewelry and only those who haven't yet been educated about the difference in terms still use semi precious to refer to a stone.

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