Gold and silver are rare metallic chemical elements that fetch high and durable economic value. They are less reactive than most elements and are made distinct by their luster and their high melting points. The best known metals are gold and silver whose uses range widely from jewelry to coinage to art, as well as in the past years, have been recognized for their industrial significance as well. Platinum, which was basically a waste product, has become becoming one of the most widely traded precious metals and include ruthenium, rhodium, palladium, osmium, and iridium. The nature of gold and silver might be produced from the fact that they are very scarce and unique among other commodities which also account for their quality to be judged to become of effective monetary value, thus, a measure of wealth. It's also important to take into account that not every precious metals stay precious forever. This relies on their own availability and new ways of refining or perhaps creating such. Take aluminum, for example, once hard to outside of ore, it used to be the most difficult metal to obtain despite being one of the most common. Its status, which once place it above gold, dropped significantly when a simple aluminum extraction method is discovered in the late 1800's.
Fluctuations as to the rarity of metals depend on demand. Silver, for one is within a supply deficit, using more silver than it is mined, and is then projected to cost even more than gold soon.
Apart from rarity, other common characteristics of metals such as uses, easy storage, similar origin and historical value are thought as criteria to be distinguished as gold and silver. It's also difficult to deny the industrial purposes of gold and silver which make them even more appealing. Finding new ways to use them increases their market price in the trade and commodity market.