How to Identify Jewelry Trademarks

Used jewelry has become big business for jewelers and other small businesses, especially since the price of gold passed $1,000 per ounce several years ago. Interpreting the tiny marks stamped on jewelry helps to establish its value. Stamps may specify the metals used to make the jewelry and the name of the manufacturer. Although not all jewelry carries stamps, valuation of jewelry usually begins by looking for these identifying marks.

Jewelry marks are tiny, so it helps to look at jewelry under magnification. Jewelers typically use a specialized loupe with 10x magnification, which makes items appear 10 times larger. Some individuals prefer to use a larger magnifying glass or a microscope. Look for letters, words or numbers stamped in an inconspicuous place. These are often found inside rings, on the bail or underside of pendants, on the clasp of bracelets and on the posts of earrings.

One of the first considerations in evaluating jewelry is to determine its composition. Fine jewelry is made of intrinsically valuable materials such as precious metals and genuine gemstones. Costume jewelry is typically constructed of base metal that may be overlaid in some manner with a thin layer of gold or silver. It is set with imitation or simulated gems.

The most commonly found stamps on fine jewelry are hallmarks, also called purity or quality marks. These identify the relative proportion of precious metals -- gold, silver and platinum -- used in fine jewelry. Initially established in 13th century England, hallmarks vary by country and time period. Contemporary U.S. jewelry uses the karat system, with 24 karats representing 24 out of 24 parts gold, or pure gold. A 14-karat gold item contains 14 out of 24 parts gold and is stamped 14k. Sterling silver is usually marked "Sterling" or "925," to indicate that it is 92.5 percent pure silver. Platinum is typically stamped with the initials PT or abbreviation PLAT.

Quality marks are also used in costume jewelry to describe the method with which gold or silver has been applied over base metal. Gold-filled jewelry has a layer of at least 10k gold and is often stamped G.F. or R.G.F. There are dozens of stamps used to describe different methods of plating gold. For example, G.E. represents Gold Electroplate.

Alone or near the quality mark, you may find a trademark or maker's mark. A trademark is the name, logo or initials of the jewelry's manufacturer, importer, wholesaler or retailer. Trademarks have been registered with the U.S. Patent Office or with another country's patent office. Maker's marks are similar to trademarks but are unregistered. Trademarks and maker's marks have been used for hundreds of years on both fine and costume jewelry. Some companies have used different marks over their history. If you are unfamiliar with the name or symbol, consult a guide to identify the maker.