Gold has been used for coins, jewellery and decoration for thousands of years. Gold is prized for its rarity, beauty, durability and the unique qualities that enable the jeweller to craft it into almost any form desired. In order to vary its colour and increase its hardness, gold is almost always alloyed with other metals. The purity of gold jewellery is expressed in karats, which is a measure of gold content or percentage. Gold jewellery is “hallmarked” to indicate the content of gold, ie: 10k, 14k, 18k, 19, or 24k, 24k being pure gold.
Of all the precious metals, platinum is the most rare and the most valuable. Denser than gold, it is inert and thus very resistant to corrosion. Platinum is very strong, yet is soft and easy to carve. Platinum settings for gemstones last for years and years. Most platinum jewellery is alloyed with 5% of other metals, giving it a standard hallmark of 950.
Pure silver has an exceptionally bright, silver-white colour that readily tarnishes upon exposure to air. Too soft to be used in jewellery in its pure form, silver is alloyed, usually to 7.5% with other metals , giving it the characteristic hallmark of 925, or “sterling” silver. Less rare than gold or platinum, silver is an affordable and beautiful choice for jewellery. Most fine silver jewellery is plated with rhodium, a bright white metal, in order to make the silver jewellery more tarnish resistant.
Rhodium and Palladium
Hard white metals from the platinum group of the elements, rhodium and palladium are used in jewellery making to make white gold whiter and to plate silver and white gold jewellery.