Silver is the precious metal for the rest of us. Recently, its preciousness has increased in the commodities market, along with that of gold and platinum. Just a few years ago, silver was selling for about five to six dollars per ounce. As of April, 2007, the spot price hovers between 13 and 14 dollars, and it has seen 15 dollars per ounce not so long ago.
In its native form, silver appears in flakes, forms something like wire and massed forms, even, rarely, as large as 1500 pounds. Today, silver is a byproduct in the refinement of gold, lead, copper and zinc ores. The silver is recovered from these metals in the refining process or extracted from ores by various processes, such as smelting.
The melting point of silver is 1780.9oF, 960.5oC, which is lower than that of gold. Sterling silver melts at the slightly lower point of 1640oF, 893oC. Silver’s malleability and ductility run second only to gold. It is the whitest metal and polishes to a luster of high reflectivity, to the great chagrin of photographers of silver objects.
Like gold, silver’s pure form is too soft, and it is alloyed to harden the metal and increase durability. The most common alloy is, of course, sterling silver, which contains 92.5% fine silver and 7.5% copper. This is the origin of the phrase “925 Sterling Silver.”
Unlike gold, silver tarnishes when exposed to sulphur, and given the sulphur in urban air, it’s impossible to prevent tarnish in fine silver or sterling silver. Warding it off is possible to some extent with anti-tarnish plastic bags, strips or blocks, and polishing will restore the gleaming shine.
Tarnish-free sterling silver is more nearly possible with rhodium plating or the use of an alloy of sterling silver called Argentium®, which contains deoxidizers. However, freedom from tarnish usually costs a bit more.
And the spot price for platinum? Somewhere around $1,300 per ounce as of April, 2007. But it’s worth it if you can get it. This metal is hard and durable, does not tarnish, and is the jeweler’s choice for a setting for diamonds, beautifully setting off their white brilliance.
Platinum was rare until 1822, until large deposits were found in the Ural Mountains in Russia. A group of related rare or noble metals that are residues of platinum ore are osmium, iridium, palladium, rhodium and ruthenium.
As with gold, platinum is found in fine grains and nuggets in alluvial material, such as riverbed soil or rock. Platinum is also refined as a byproduct from nickel ores.
The jewelry market makes wide use of platinum because of its hardness, ductility, malleability and resistance to corrosion. In fact, this market accounts for 50% of the total production of platinum. Alloys with five or ten percent ruthenium or iridium are used since they are harder than pure platinum. The term 950 Platinum refers to an alloy of 95% platinum, and 900 Platinum to an alloy of 90% platinum.