l, stainless steel, cast iron, tool steel,alloy steel); the addition of silicon will produce cast irons, while the addition of chromium, nickel and molybdenum to carbon steels (more than 10%) results in stainless steels. Other significant metallic alloys are those of aluminium, titanium, copper and magnesium and bronze.
Bonding and Plating - There are different grades and methods of bonding precious metals to a less expensive base metal. Many jewelry items are made of either plated, bonded or filled metals. This is done to keep the cost of these items as low as possible.
- Filled Metals - have one or more layers of precious metal bonded to a base with heat and pressure. Filled materials are at least 1/20 precious metal by weight. Filled metal objects are marked with a quality stamp such as 12k GF or 14k GF.
- Flash or plate - These terms refer to the thinnest gold, silver, platinum or rhodium coating. There is no standard thickness.
- Electroplated - In this process, metals are electrolytically deposited on a base. These metals have a required minimum standard thickness - usually 15 - 25 mils (millionths of an inch). Heavy Gold Electroplate has a minimum thickness requirement of 100 mils to be stamped: (HGE).
- Clad - A composite metal containing two or more layers that have been bonded together. The bonding may have been accomplished by co-rolling, co-extrusion, welding, diffusion bonding, casting, heavy chemical deposition, or heavy electroplating. It is thought to be a good technique for coating as there seems to be an increase life-time of wearing part by 6-7.
- Gold, Platinum or Silver Filled - A layer of karat gold, platinum or silver is mechanically bonded to a base metal, usually brass or steel. Gold filled is marked with the gold percentage by weight and the karat value. If a piece of jewelry is marked 1/20 14K GF - 5% or 1/20th of the total weight is 14K gold.
- Vermeil - Gold plated over silver. Silver is the "base" metal. Typically 100 mils (millionths of an inch)must be the thickness of the gold plate to be called vermeil.