Silver, gold and platinum group metals (platinum, palladium, rhodium, ruthenium, iridium and osmium) are considered noble or precious metals. All precious metal alloys are nonferrous, meaning that they do not contain iron.
- Precious metals are valued for their beauty and rarity. Because of their value, they have long been used as mediums of monetary exchange and as a means to ensure economic stability in countries (Oldershaw, 2003:205).
- Precious metals are also chemically stable and they resist oxidation and corrosion from acids, which not only makes them especially suitable for use in fine jewellery (Untracht, 1985:30), but also makes them useful in various other industries (Oldershaw, 2003:205).