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About Silver

Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
Fine silver, for example 99.9% pure silver, is relatively soft, so silver is usually alloyed with copper to increase its hardness and strength. Sterling silver is prone to tarnishing, and elements other than copper can be used in alloys to reduce tarnishing, as well as casting porosity and fire scale. Such elements include germanium, zinc, platinum, silicon, and boron. Recent examples of alloys using these metals include argentium, sterlium, sterilite and silvadium.
About Copper
Copper is a soft, malleable, and ductile metal with very high thermal and electrical conductivity.
A freshly exposed surface of pure copper has a pinkish-orange color.
Copper ranks as the third-most-consumed industrial metal in the world, after iron and aluminum, according to the U.S Geological Service (USGS). About three-quarters of that copper goes to make electrical wires, telecommunication cables and electronics. 
Aside from gold, copper is the only metal on the periodic table whose coloring isn't naturally silver or gray.
About Gold
In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal.
It is one of the least reactive chemical elements and is solid under standard conditions. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloride acid.
A relatively rare element, gold is a precious metal that has been used for coinage, jewelry, and other arts throughout recorded history.