Aluminum is a soft, durable, lightweight, malleable metal with appearance ranging from silvery to dull grey, depending on the surface roughness. Aluminium is remarkable for the metal's low density and for its ability to resist corrosion. It is easily machined, cast, drawn and extruded.
Brass is an alloy of copper and zinc. Since copper is a highly active metal, tarnishing is quite common. Many people notice that their skin will turn green from wearing brass. This is the result of a chemical reaction between the copper in the alloy and the normal acidic condition of the skin. To clean, use a copper/brass cleaner. Brasso and Bon Ami are suitable, but will slightly reduce the original high gloss finish.
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive, but sometimes with other elements such as phosphorus, aluminum, or silicon. It is hard and brittle, and it was particularly significant in antiquity, giving its name to the Bronze Age.
Copper is one of only two elemental metals that have color. Since copper is a highly active metal, tarnishing is quite common. Copper often comes with a patina and therefore care should be used in cleaning. Copper cleaners will remove patinas. If no patina has been applied you can use a copper cleaner or rouge cloth.
Because of the softness of pure 24kt gold, it is usually alloyed with base metals for use in jewelry, altering its hardness, ductility, melting point, color and other properties. 22kt, 18kt, 14kt or 10kt gold contain higher percentages of copper, other base metals, silver or palladium in the alloy and lower amounts of gold. Copper is the most commonly used base metal, yielding a redder color. Jewelry with higher gold content is more prone to scratch or bend.
Rose gold is an alloy of gold and copper, typically 18 parts gold, to 6 parts copper.
Blue gold can be made by alloying with iron and purple gold can be made by alloying with aluminum, although rarely done except in specialized jewelry. Blue gold is more brittle and therefore more difficult to work with when making jewelry.
14kt and 18kt gold alloys with silver appear greenish-yellow and are referred to as green gold.
White gold alloys can be made with palladium or nickel. White 18kt gold containing 17.3% nickel, 5.5% zinc and 2.2% copper is silvery in appearance. Nickel is toxic, however, and its release from nickel white gold is controlled by legislation in Europe. Alternative white gold alloys are available based on palladium, silver and other white metals, but the palladium alloys are more expensive than those using nickel. High-carat white gold alloys are far more resistant to corrosion than are either pure silver or sterling silver.
The Japanese craft of Mokume-gane exploits the color contrasts between laminated colored gold alloys to produce decorative wood-grain effects.
Gold fill is a term used to describe a material that has been laminated with a karat gold before it is made into sheet or wire for use in jewelry making. Karat gold is bonded to a rod or brick of bronze alloy (copper and tin) with silver solder, heat and pressure. The metal is then annealed and rolled into wire or sheet. Gold filled standards require the karat gold layer to comprise 5% of the total weight of the piece. Because gold fill is a bonded metal (as opposed to plated metal), it will not lose its gold appearance through wear or polishing.
Gold fill wears well and gives the look of gold at a fraction of the price. It is a more expensive material than sterling and more difficult to handle in the process, hence the higher cost. Gold fill should be cleaned with a rouge cloth.
Gold plating is a process in which a thin gold layer is electroplated onto a base metal comprised usually of aluminum and tin. Sometimes a coating of laquer is used to protect the plating. Gold plate should not be rubbed with a polishing cloth as the gold layer is very thin and will come off over time. To remove tarnish, wash with mild soap and warm water and pat dry with a soft cloth. For objects which rub against the skin like rings and bracelets, everyday wear is not recommended.
Niobium is a rare, soft, grey, malleable metal. Niobium can be electrically heated and anodized, resulting in a wide array of colors using a process known as reactive metal anodizing which is useful in making jewelry. The fact that niobium is hypoallergenic also benefits its use in jewelry.
Palladium has been used as a precious metal in jewelry since 1939, as an alternative to platinum or white gold. This is due to its naturally white properties. The principal use of palladium in jewelry is as an alloy in the manufacture of white gold jewelry.
As a pure metal, platinum is silvery-white in appearance, lustrous, ductile, and malleable. Platinum's resistance to wear and tarnish is well suited for making fine jewelry. Platinum finds use in jewelry, usually as a 90-95% alloy, due to its inertness and shine.
Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. Fine silver (99.9% pure) is generally too soft for producing functional objects; therefore, the silver is usually alloyed with copper to give it strength, while at the same time preserving the ductility and beauty of the precious metal. Other metals can replace the copper, usually with the intent to improve various properties of the basic sterling alloy such as reducing casting porosity, eliminating firescale, and increasing resistance to tarnish. These replacement metals include germanium, zinc and platinum, as well as a variety of other additives, including silicon and boron.
Sometimes called the "space age metal", it has a low density and is strong, lustrous, corrosion-resistant with a silver color.
Vermeil is the process of coating a silver object with gold, usually 23-karat gold over sterling silver. Sometimes vermeil is lacquered so that no cleaning should be necessary. Never use a rouge cloth on vermeil. Vermeil should be cleaned by dipping into a solution of warm water and mild detergent. Gently pat dry. Do not rub. Rubbing the surface will remove the gold finish with time. For objects which rub against the skin like rings and bracelets, everyday wear is not recommended as the gold layer will wear off.