Precious Metals

Metals are a group of chemical elements that exhibit all or most of the following physical properties. There is a consistent solidarity at ordinary temperatures except in extremely thin films, good conductivity for electricity and heat, high reflectivity for light when polished, and crystalline structure when in the solid state. There are many different varieties of metal, but the jewelry industry is concerned with copper, gold, iridium, nickel, palladium, platinum, rhodium, silver and titanium. Of these metals, gold, platinum, silver and in some cases rhodium and titanium are used for precious jewelry. Metallic elements can combine with one another and with certain other elements, either as compounds, as solutions, or as intimate mixtures known as alloys.

Within the general limits of the definition of a metal, the properties of metals vary quite widely. Most metals are grayish in color, but copper and gold are red and yellow respectively. The majority of metals crystallize in the cubic system, but some crystallize in the hexagonal and tetragonal systems. Silver has the highest electrical conductivity at ordinary temperatures. The conductivity of most metals can be lowered by creating alloys. All metals expand when heated and contract when cooled.