The majority of the findings I use are electroplated, either silver or gold, over brass. I have also begun using copper filled sterling, which is silver electroplated over copper. In electroplating a coating of silver or gold is chemically deposited on base metal. The coating layer is then bonded to the base metal via electric current. The quality of plating is determined by the thickness of the coating. For silver-plated items they can also be given a coat of lacquer to prevent tarnishing. Yes, silver plate does tarnish - it is silver!
Choosing to use plated findings allows me to keep my prices very affordable and I feel it does not sacrifice quality. I have sliver-plated earrings that I have worn for many, many years. A few have become discolored with a patina, but most look just as they always have. Please visit this post that I did last July to learn more about silver plate.
Here are some of the other metals I use in my work and their components:
Brass is 70% copper and 30% zinc.
Bronze is an alloy of copper and tin
Gunmetal is 85% copper, 5% tin, 5% lead, 5% zinc. Often plated over brass or surgical steel.
Argentinium silver is a mix of silver, copper and germanium
Sterling Silver, sometimes stamped .925, is an alloy of at least 92.5% silver, and (usually) copper
Surgical and stainless steels are slightly more gray than silver. Mixture of steel, chromium, and nickel. Surgical stainless steel used in jewelry has approximately 8% nickel, but it is so tightly bound that it cannot leach out and this is why it is recommended for people with metal allergies.
Pewter includes any of the numerous silver-gray alloys of tin with various amounts of antimony and copper. Most products are made with a lead-free pewter and have a surface finish over the pewter. "Antique pewter" or "antique brass" may be brass or zinc with an antiqued pewter or antiqued brass plating. In nearly all cases, these zinc or brass alloys meet lead-free criteria.
Gold or Silver plate is a very thin deposit of real gold or real silver, electroplated or electrochemically applied to the piece. It about 1/1,000-1/1,000,000 of an inch thick. Heavy electroplate might be 2 or 3/1000s of an inch thick (this can also be written as 2 or 3 mils).
Niobium is hypoallergenic and is a great alternative for people who are sensitive or allergic to other metals. Represented with the symbol Nb, it is mined from the crust of the earth. Because it is such a rare metal, it is worth several times the value of silver. In jewelry niobium is put through an anodizing process that brings out the metal's characteristic iridescence. The colors do not rust or come off, but may become dull over time. Niobium jewelry, though sturdy, should be treated gently. Clean it with soapy water and dry it off by rubbing it lightly with a dry towel.