English Glossary

A

Alloy - A metal composed of two or more metals; sterling silver is an alloy of fine silver and copper.

Annealing - Heat-treating a metal to a temperature below its critical range, mainly to relieve residual stresses but also to render the metal soft for further cold working.

Anode - The positive pole of an electrolytic cell, usually the supply source of the metal being deposited. 

B

Base metal - Non-precious metal, such as aluminum, copper, iron and nickel.

Bezel - The rim of metal that is used to secure a stone in a rub-over setting. 

Bossing - Beating a sheet of metal from the back to a required form; also known as embossing.

Burnish - To polish and work-harden metal by rubbing, usually with a polished steel tool. 

Burr - A sharp or rough edge that occurs on the edge of the metal, usually after cutting. 

C

Cabochon - A stone made of a semi-precious material ground into a rounded or domed shape usually with a flat back. 

Carat - A unit of weight, now standardized as being equal to one-fifth of a gram; this is equal to 3.086 grains Troy. The weight of gemstones is usually expressed in carats. 

Casting - The process of pouring molten metal into a mold. Also the name given to the result. 

Cathode - The negatively charged pole in an electrolytic cell on which the metal is deposited. 

Chasing - The process of punching a relief design in metal from the front. 

Chenier - Thin metal tube, often used for making hinges in jewelry. It can also form other parts of a piece. 

Crucible - A refractory container for metal that is to be melted. 

Culet - The small facet on the base of some brilliant-cut stones.

D 

Damascene - A metal-decorating process that involves the application of one metal on another by encrustation or inlay. 

Dapping block - The cube-shaped metal tool with semi-circular depressions on all sides used in conjunction with dapping punches for making domed metal forms.

Die - A tool used for shaping by stamping or press forming. 

Drawplate - A hardened steel plate with a series of holes of various sizes. Wire is drawn through the plate to reduce its thickness, or to change its shape. Draw plates are commonly available with round, square or triangular holes. 

Drilling - Using a hand drill or flexible shaft installed with a twist drill to make a hole into metal.

E 

Electroforming - The process of forming metal objects by using an electric current to deposit the metal in a mould. The mould must be coated with a substance that conducts electricity. 

Electroplating - The process of depositing a thin layer of metal on an object by means of an electric current. 

Engraving - The process of cutting away the surface of a substance, using a sharp steel tool called a graver. 

Etching - The controlled corrosion of a surface with acid. In jewelry, the process is used to form surface decoration on metal: some parts of the surface are protected by an acid-resisting substance, while others are eaten away by the acid. 

Exothermic - A chemical reaction that gives off heat as a by-product.

F 

Facet - A flat surface ground on a cut gemstone. 

Ferrous - Containing iron. 

Filigree - An open ornamental structure utilizing all forms of wire soldered together into small and large units. 

Findings - Mass-produced jewelry components, such as catches, joints and clips, which are commonly used, even on handmade jewelry. When such components are made by hand, they are sometimes called fittings. 

Firestain (Firescale) - The black coating that forms on silver when it is heated. The coating consists of copper oxide and is formed by the copper in the impure silver combining with oxygen in the air. 

Fluidity - The ability of a molten metal to flow readily when heated to a certain temperature. 

Flux - A substance used in soldering to ensure that the solder flows. Any oxide present on the metal tends to prevent the solder from flowing. The flux is applied to the parts to be soldered and prevents air from reaching them. As a result, no oxide is formed, so the solder is able to flow and join the metal. 

Foil - Sheet metal usually not more than 1.005 inch thick. 

Forging - The process of hammering metal to change its shape. 

Fretwork - A sheet that has been pierced with holes or shapes to make an ornamental pattern. 

G

Gallery - A wire fixed to the back of jewelry to raise the level of the metal so that there is sufficient clearance below for the stones. 

Gauge - A standard unit of measurement of the thickness of sheet or the diameter of wire. 

Girdle - The widest circumference of a gemstone. The girdle forms the boundary between the crown (top) and the pavilion (base). 

Gold leaf - Gold that is beaten or rolled into extremely thin sheets. 

Grain - A unit of weight, common to both the Troy and Avoirdupois systems. Four grains are equal to one carat, the unit of weight for precious stones and pearls. 

Granulation - The decoration or texturing of a surface by the application of tiny balls of gold or silver. 

Grinding - The removal of metal by holding it against a revolving device, such as motor-mounted abrasive wheels, bands, discs, or belts.

H 

Hallmark - A series of impressions made in an item of gold, silver or platinum. The hallmark is an official guarantee of the fineness of the metal. 

I

Intaglio - An object with a hollowed-out design, the flat surround being the highest part. 

Investment - Fine-grade plaster used in the casting process. 

M

Malleability - The property, usually of a metal, of being easily hammered, rolled or pressed to shape without fracturing. 

Mandrel - A steel or wooden shape for supporting metal while it is being hammered. 

Marquise - Any gemstone with a boat-shaped girdle. The curved sides meet at a point at each end of the stone. 

P

Pallions - Small pieces of solder, taken from the French word for ‘flake’. 

Patina - A surface finish that develops on metal or other material as a result of exposure to chemicals or handling. 

Pickle - A solution used during construction to clean flux and oxides from metal after heating. 

Piercing saw - A saw with a blade narrow enough to be threaded through a drilled hole so that a pattern can be cut out from sheet metal or other material. 

R

Repousse - A relief design punched into metal from the back. 

Rouge - Jeweller’s rouge is red iron oxide, a fine abrasive used for the final polishing stages of precious metals. 

S

Shank - The part of the ring that passes around the finger. 

Soldering - The process of joining metal, using an alloy called solder. The solder is designed to melt at a temperature lower than the metal it is intended to join. The work and solder are heated until the solder melts. On cooling, it solidifies to form a firm joint. The terms easy, medium and hard solder describe solder with progressively higher melting points. Thus, some joints can be made at a relatively low temperature without melting earlier joints made with a high melting point solder. 

Sprue - The unwanted piece of metal attached to a casting and formed by the access channel in the mould. 

Stamping - The process of forming a pattern in sheet metal using a punch bearing the complete design. The pattern is formed by a single blow and the process is suitable for mass production. 

Swaging - The process of making metal U-shaped by hammering into a U-shaped groove in a metal block. 

T

Tempering - The process of heating metal after hardening to reduce its brittleness. 

W

Work-hardening - The hardening of a metal caused by hammering or bending, which often makes the metal too hard to work with until it has been softened by annealing.