All about Precious Metals

They are usually ductile and have a high lustre. Historically, precious metals were important as currency but are now regarded mainly as investment and industrial commodities.

The best-known precious metals are the coinage metals, gold and silver. Although both have industrial uses, they are better known for their uses in art, jewellery, and coinage. Other precious metals include the platinum group metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum, of which platinum is the most widely traded. The demand for precious metals is driven not only by their practical use but also by their role as investments and a store of value. Historically, precious metals have commanded much higher prices than common industrial metals.

Precious metals all have high densities (specific gravities ranging from silver at 10.5 to iridium at 22.6), relatively good corrosion resistance, good electrical conductivity, and relatively high value. Despite the latter factor, they are often economically acceptable because of their properties and performance in service. Scrap values are high and recycling is common.

Precious metals have a higher melting point than normal metals, which means that they require large amounts of heat and electricity to be melted and then reshaped. Gold, Silver and Platinum have a very shiny appearance (lustre), which is why they are used for ornamental art and jewellery. Their ductile quality means they can be shaped into any form without being broken.

Fineness is used to designate the purity of gold and silver in parts per thousand by weight; hence, 995 fine gold is 99.5% gold, and 925 fine silver (sterling silver) is 92.5% silver. Jewellery is specified in karats, where 1 karat is 1/24th part of gold; hence, for example, 18 karat gold is 75% gold.

Characteristics of precious metals:
A higher melting point than other metals
Softer in texture – which is also referred to as being ductile
More lustrous in appearance
Less reactive than other elements