Purity
Gold
Pure gold is a relatively soft and malleable metal that is too soft for most forms of jewellery. Other metals such as silver and copper are added to gold to make it stronger and in some cases change its colour.
White metals such as silver can be added to make white gold. White gold is commonly given a finish of white rhodium that provides a harder and shinier surface.
Copper is the metal alloy added to create rose gold.
The purity of gold is measured in carats. Pure gold is described as 24 carat gold. If a ring is made with 75% gold and 25% alloys, it is described as 18 carat gold (75% of 24 is 18). Sometimes you wiill see the figure 750 inside 18-carat gold rings.
A 14 carat gold ring contains 58.5% gold, and a 9-carat gold ring, 37.5% gold. You will sometimes see the number “585” or “375” inside a ring.
Internationally, the weight of pure gold is measured in troy ounces. 1 troy ounce is around 31 grams.
Silver
As with gold, pure silver is too soft for some forms of jewellery and so metal alloys will be added to provide greater hardness and durability. Sterling silver is 92.5% silver and 7.5% other metals.
Sterling silver can tarnish and needs an occasional clean. It may be finished with rhodium to provide a stronger and shinier surface that is less subject to tarnishing.
