Glossary

 

The following are definitions and helpful information for technical terms commonly used in the jewelry manufacturing industry and by silversmiths.

 

Acid Test: A method for determining the fineness of gold by subjecting it to various acids. For testing up to 10K gold, nitric acid is used. Gold finer than IOK reacts only with a mixture of nitric and hydrochloric acids known as aqua regia.

 

Alloy: A combination of two or more metals usually formulated to provide or increase desired properties, such as ductility, conductivity, durability, etc.

 

Assay: Analysis of a metal to determine its purity.

 

Rase Metals: Non‑precious metals such as copper, zinc, nickel, etc.

 

Britannia Metal: A composition of tin, copper and antimony.

 

Casting: The method of duplicating an object by pouring metal into a hollow mold formed by the original object. Almost any jewelry object which can be made by hand can be reproduced by the lost wax or centrifugal casting process.

 

Coin Silver: An alloy of 90% fine silver and 10% copper.

 

Colors of Gold: Yellow, green, red and white are produced by variations in the alloy. Silver and zinc tend to give a green color, copper‑red, and nickel‑white.

 

Commercial Silver: Silver that is 999 fine or higher.

 

Danish Silver: Silverware made in Denmark is 830/1000 fine silver if made to minimum Danish standards. 925/1000 fine silver is made for export.

 

Ductility: Capability of being drawn out or hammered thin. Gold is the most ductile of all metals.

 

Electroplating: In the jewelry industry, the use of electricity to deposit a thin layer of precious metal on the base metal of a jewelry item.

 

Filigree: Ornamental work in which fine wire, usually of gold or silver, is twisted and soldered into intricate patterns.

 

Florentine Finish: A textured surface for gold and silver produced by engraving a series of parallel lines in one direction, then cross‑hatching them more lightly at a 90 degree angle.

 

Fool's Gold: Common name for iron pyrite, which is sometimes mistaken for gold. Iron pyrite is hard and brittle, while gold is soft and malleable.

 

German Silver: Another name for nickel silver. A composition of nickel, copper and zinc, it contains no silver.

 

Gilding: The coating of a surface with a thin layer of gold. Electroplating is the modern form of gilding.

 

Gold Filled: Bonding a layer (or layers) of gold alloy to a base metal and then rolling or drawing the metal to the thickness desired. The gold content must be 1/20th or more of the total weight of the metal in the piece.

 

Hallmark: An official mark stamped on gold and silver articles to attest to their purity.

 

Handmade: A term which can be applied only to jewelry objects made entirely by hand, without the use of machine tools.

 

Handwrought: This term implies that the jewelry article was made partly by machine and partly by hand.

 

Karat: A measure of fineness; 24 karat is fine gold. One karat equals 1/24 (.0417%), so that 14 karats is 14/24 fine gold and the balance (10/24) alloy. If the gold content of an alloy is less than 10/24 the object cannot be represented as karat gold.

 

Nickel Silver: A composition of nickel, copper and zinc. It contains no silver. Also known as German Silver.

 

Pennyweight: The twentieth part of a troy ounce. The name originally applied to the weight of an AngloNorman penny.

 

Precious Metals: Gold, silver and the platinum group metals are known as the precious metals. They are also called the noble metals by some craftsmen.

 

Rolled Gold Plate: The same type of gold covering on a base metal as gold filled, except that the quantity of karat gold is less than 1/20 of the total metal weight. Must be identified with a fraction indicating the quantity of gold.

 

Roman Gold: A finish on gold jewelry produced by matting or frosting the surface, then electroplating it with pure gold. This provides a soft matte finish with a rich yellow color.

 

Rubber Molds: Though lost wax castings using clay molds were made for thousands of years by craftsmen in many parts of the world, it wasn't until the perfection of a rubber mold (in the 1930s) to produce many wax patterns quickly and inexpensively that the technique became practical for manufacturing jewelry.

 

Sand Blasting: A means of producing a matte or frosted finish on gold and other metals. This is accomplished by holding the work against a stream of sharp sand driven by a jet of compressed air.

 

Sheffield Plate: Originally made by bonding sheet silver to copper, rolling and manufacturing the bonded metals into hollowware. Imitations are made by electroplating silver on copper and are sometimes erroneously advertised as Sheffield plate.

 

Silver Plated Ware: Made by electroplating fine silver on a base metal alloy ‑usually nickel silver or Britannia metal, sometimes brass or copper.

 

Solid Gold: Fine old or gold of 24 karat. The term "solid gold" should not be applied to articles of lesser quality.

 

Sterling Silver: Must be 925/1000 (92.5%) fine silver and 75/1000 (7.5%) copper. This proportion is fixed by law.

 

Troy Ounce: From the troy system of weight used for measuring precious metals, based on a pound of 12 ounces and an ounce of 20 pennyweights or 480 grains. Precious metals are measured in troy ounces worldwide.

 

White Metal Alloy: For jewelers, white metal (babbit) alloy is tin and antimony.