Gold and silver are rare metallic chemical elements that fetch high and durable economic value. They're less reactive than most elements and therefore are made distinct by their luster as well as their high melting points. The best known metals are silver and gold whose uses range widely from jewelry to coinage to art, as well as in yesteryear years, happen to be renowned for their industrial significance too. Platinum, that was basically a waste product, is now becoming one of the most widely traded gold and silver and can include ruthenium, rhodium, palladium, osmium, and iridium. The character of precious metals may be derived from the truth that they're very scarce and unique among other commodities that also account for their quality to be judged to become of effective value, thus, a measure of wealth. It is also important to consider that not all precious metals stay precious forever. This depends on their availability and new ways of refining or even creating such. Take aluminum, for instance, once hard to outside of ore, it was once the most challenging metal to obtain despite being probably the most common. Its status, which once put it above gold, dropped significantly when an easy aluminum extraction method is discovered in the late 1800's.
Fluctuations regarding the rarity of metals depend on demand. Silver, for one is in a supply deficit, using more silver than mined, and is then projected to cost even more than gold soon.
Aside from rarity, other common characteristics of metals such as uses, easy storage, similar origin and historical value are thought as criteria for being distinguished as gold and silver. It is also hard to deny the economic uses of precious metals which make them much more appealing. Finding new ways to use them increases their market value within the trade and commodity market.