Jewelry can be made of many materials.  Each one has it's own special characteristics.  Color, malleability, melting temperature, and wearability each need to be considered when creating a piece of jewelry.

Gold

Silver

Copper

Gold   Gold was one of the earliest precious metals to be worked.  It never tarnishes, and is very easy to forge, hammer, cast, and shape.

Melting Point:
1945 degrees F

Gold Plated    When gold is plated onto the surface of another metal, it is a microscopic film of gold, and easily scratches or wears off over time.

Gold Filled    This means that a layer of gold has been bonded onto another material, usually brass, by treating the metals with heat and pressure bonding a thin layer of gold onto the top of the core metal.  Jewelry made of gold filled wire or sheet can withstand more wear than gold plated, but still can scratch, and cannot be hammered, or the underlying metal will show through.  Gold filled wire is used for the properties of gold (color, the fact that it does not tarnish).  But, since gold filled wire contains little actual gold, the price of the material is so much less expensive.  For example, a one foot length of 14K gold wire would be about $44, compared to $3 of gold filled wire of equal size. 

Karats    This term defines how much gold is actually in a piece of metal.  Gold is mixed with various other metals, in various percentages.  Yellow gold is gold, copper, silver, and zinc.  White gold is gold, copper, nickel, and zinc.  Pink gold (sometimes called old gold) is gold, copper, and zinc.  10K gold contains 41 percent gold, 12K 50 percent gold, 14K 58 percent gold, 16K 66 percent gold, 18K 75 percent gold, 20K 83 percent gold, 22K 91 percent gold, and 24K gold is 100 percent gold.  24K gold is rarely used because it is so soft.  The more gold present in the material, the more valuable, and the quantities and mixtures of base metals will show as different colors.

Testing Gold    To determine if a metal is gold or some other metal, nitric acid is dropped onto the scratched surface.  To determine which carat the gold is, samples of known karats must be used along with the nitric acid.   These tests are usually done in a testing laboratory.

Gold

Silver

Copper

Silver    Silver has been worked for centuries.  It does tarnish, but can easily   forged, shaped, cast, and shaped.

Melting Point: 1761 degrees F

Nickel or German Silver    This metal actually has no silver in it.  It is an alloy of copper and nickel.

Silver Plated    When silver is plated onto the surface of another metal, it is a microscopic film of silver, and easily scratches or wears off over time.

Coin Silver    This alloy contains 10 to 20 percent copper, and only 70 to 80 percent silver.  It can be made into jewelry, but will tarnish more easily than sterling.

Sterling Silver    Pure silver, like pure gold, is too soft for most uses and is often mixed with copper.  Sterling silver is 925 parts fine silver and 75 parts copper, and is also known as .925.  This alloy will tarnish, but the copper is necessary in jewelry like rings, brooches, necklaces, and other items that require metal with strength. 

Fine Silver    Fine silver is 100 percent silver.   It has a brilliant white color, and is the whitest of all metals.  It will not tarnish, and is frequently mixed with gold.  It is a very soft metal, and will not withstand wear.  It is commonly used in a very fine wire form, as in knitting with fine silver wire. 

Gold

Silver

Copper

Copper    Copper is widely used in industry due to it's ability to conduct heat and electricity very well.  It is very easy to form, color, and shape.  It has been used for centuries in jewelry, weapons, vessels, and other art objects.

Melting Point: 1981 degrees F

Properties    Copper is usually mixed with other metals to toughen and strengthen the alloy.   It's ability to repeatedly softened (annealed) and hardened make it ideal for forming, forging, and shaping.  Copper tarnishes easily and needs frequent polishing.   When it is exposed to moist air, poisonous substances are formed on the metal.   So, people who work with copper need to wash hands often, so as not to ingest these substances.  That is also the reason that copper cookware and serving pieces should be plated with non-corrosive metal such as tin or washed before each use. 

Coloring    One of the wonderful properties of copper is it's ability to be heated to add a color on the surface of the metal (heat patina).  To maintain it's natural color it can be washed thoroughly, then scrubbed with steel wool.  If wax or lacquer is applied, it should not tarnish or react with the skin and make it black.  To color copper jewelry, wash it very well to remove all tarnish, grease, and dirt.  Handle it carefully and put it in the oven at about 200 degrees F.  It will go through a wide variety of color changes from reds, blues, greens, and eventually to black.  After removing it from the oven, the color will still change a bit, since the metal is still hot.  If you don't like the color you can rub the piece with steel wool and wash it again and reheat it.  When you do heat to a color you want to keep, wax it or use a spray varnish to maintain the color and reduce tarnishing.