Silver Primer

Easily worked with a variety of finishes and adaptable to many styles, silver is a favourite jewellery metal.

Silver is one of the three most popular jewellery metals, the others being gold and platinum. Among amateurs who enjoy making jewellery, silver isn’t just among the top three, it’s the metal of choice.

Silversmiths have developed many ways of working this precious metal, from the ancient hand techniques of forging and raising to the high-tech process of electroforming. Contemporary silversmiths seem to favor channelwork, etching, engraving, filigree, scrollwork, casting, applique’, and stone mounting. Silver is also a frequent component in the multi-metal techniques of married metals and mokume gane.

Just what is silver and why is it so versatile? Silver is an element and a mineral species. Its chemical symbol is Ag, from the Latin word for silver, argentum. Mineralogically, it belongs to the isometric crystal system, is 2-1/2 to 3 in hardness on the Mohs scale, has a specific gravity of 10.5, and leaves a white streak. In nature, silver often occurs with gold, copper, nickel, or other metals; silver ores include the minerals argentite, acanthite, pyrargyrite, polybasite, stephanite, and proustite. Gold that occurs with a natural silver content of about 30% is called electrum; copper-silver combinations are called halfbreeds. Major silver deposits have been found in Mexico, Canada, Norway, Chile, Australia (in New South Wales), and in the U.S. in Montana, Idaho, Colorado, Arizona, Nevada, and Michigan.

Of course, while mineral collectors are interested in the natural forms of silver specimens, silver’s trademark metallic qualities of being malleable (shaped by being beaten or rolled), sectile (cut smoothly), and ductile (drawn or hammered) and its gleaming lustre are what have made silver a favourite medium among metalsmiths for thousands of years. Among the traditional cultures of the Middle East, India, Tibet, Burma, and North America, silver has long been the preferred jewellery metal. In addition to being readily worked, silver is also relatively abundant and much less expensive than gold. Even with gold’s currently low prices (at a little over $250 an ounce in late summer), at a little over $5 an ounce for the same time frame, silver is still quite a bargain.

Jewellery makers can buy silver as wire, sheet, bullion, ingots, or casting grains. These variations also come in multiple choices; for example, the kinds of wire include round, flat, triangular, square, half round, and bezel.

The silver used for jewellery is generally either fine (pure) silver or sterling, which is 925/1000 pure silver. Coin silver is .900 parts silver. Mexican silver has varied from between .900 to .980, and is now mostly .925. Silver jewellery is usually stamped with the metal purity and the registered hallmark of the manufacturer making the claim. Different countries have different requirements about stamping, however. England and France are very strict; laws in the United States are frequently revised; some countries simply have no regulations at all. Fine silver, like gold, is sold by the troy ounce. There are 14.58 troy ounces to a pound (instead of the 16 avoirdupois ounces that are more commonly used to divide the pound), and there are 155.54 carats in a troy ounce.

Sterling silver is alloyed with copper and tarnishes easily, although pure silver is also blackened by natural oxidation. In some countries, zinc is used instead of copper to make sterling silver, but the result has a tinny appearance.

Some “silvers” contain no silver at all. German silver and nickel silver are names for alloys that look like silver but have no silver content. Other metals that may resemble silver are pewter, aluminum, and Monel metal. Recently, plastics manufacturers have come up with silver and gold look-alikes. Trade names that suggest silver, such as Morton Silver, Silverine, and Silvertone, do not contain silver as a rule, but Black Hills Silver is silver from the Black Hills. Silver-plated items generally do not have much silver, though the best quality silver-plated flatware is an exception, and very thin layers of silver, called silver leaf, are used on picture frames and other objects.

Metal items that are supposed to be silver may be tested first with a magnet. If the magnet is attracted, the item is not silver. To test a piece for silver content, place a drop of silver reagent on a notch in the metal. Pure silver will then turn bright red, while sterling will turn much darker red. Silver that is .800 will test brown, and an object that is only .500 silver will turn green.

Although silver is known as a white metal, it can also appear green, blue-green, red-brown, or purple through the application of sulfides, carbonates, chlorides, and other chemical solutions. The color of silver can also be changed by the application of thin layers of glass, as when fine silver is used in enameling, enamel being basically glass.

Sometimes, silver is intentionally blackened with potassium sulfide for an antique look.

Colour is also used to determine the heat during soldering. The melting point of fine silver is 1761F; sterling silver, 1640F; and coin silver, 1615F. As silvers heat up, they change color, and the jewelry maker can “read” the temperature by the color. The metal will be faint red between 700F and 900F; dark red at 900F-1200F; bright red at 1280F-1590F; cherry red at 1600F-1750F; and red-orange at 1800F-1850F.

Silver needs to be annealed when working it, and when to anneal can also be gauged by colour. The annealing temperature is reached with a faint dull red glow, between 900F and 1200F.

Silver solders are easy flow, medium flow, and hard flow, with hard flow having the highest melting temperature. Paste solders have flux already added.

The biggest problem jewellers face with silver is the formation of firescale, a discolouration caused by oxidation. To prevent firescale, silversmiths learn to use an adequate flame, plenty of flux, and to heat the piece quickly and withdraw the flame at the moment of flow, then pickle at once.

If firescale does occur, vigorous buffing and hot pickle may help. If results are still unsatisfactory, a process called bright dipping may be used. In this, the silver piece is attached to a wire and quickly dipped into a solution of 50% cold water and 50% nitric acid. After a dip of several seconds, the piece is rinsed and the acid neutralized with soda. (A respirator and rubber gloves are recommended for this process.) Deep firescale can also be removed with emery or pumice.

Silver is used in photography, medicine, mirrors, coinage, utensils, and other products in addition to jewellery. There have been times in the past when silver was valued more highly than gold: silver was the most valuable metal in some periods of ancient Egypt, and in 18th century France, the finest diamond jewellery was set in silver. The uses of silver for jewellery have flourished in the last few years, and while fashions come and go, silver jewellery will always be with us.

June Culp Zeitner is the author of nine gem and mineral books, the most recent of which is Gem and Lapidary Materials, and an avid artisan and collector.

This article by June Culp Zeitner was published in the Lapidary Journal Jewelry Artist Magazine.