Gold has always been regarded as the most important metal for jewellery because of its rich colour, malleability, durability and pure beauty.
Gold is rarely used in its purest state (24 Carat), because it is so soft. It is usually “alloyed” (mixed with other metals), with either copper, silver or a combination of copper and silver. Its natural colour is yellow, but when mixed with other metals gold can produce a pure white metal or a yellow metal with hints of red or green.
The quality of gold is judged by its “carat value”, which refers to the percentage of gold within the metal. The highest carat weight used in jewellery is 22 carat (22ct), containing 91.66% gold, although this produces a very soft metal.
Also widely used in jewellery is 18 carat (18ct) with 75% gold content, and, 14 carat (14ct) with 58.5% gold content. These two gold grades tend to be used in high-quality pieces because they still enjoy the rich and beautiful colour of 22ct gold but are harder wearing.
Finally, 9 carat (9ct) with a gold content of 37.5% is the least expensive and the most widely used in modern high street or retail jewellery. 9ct gold is very useful for items requiring extra strength, such as chains and necklaces, and with the current high price of gold, 9ct is increasingly becoming the norm for most people’s budgets.
In 1854, when jewellery contained a much higher gold content, because gold was a lot cheaper than it is today, 12ct and 15ct were introduced as a harder-wearing alternative to the softer 18ct and 22ct gold. 12ct and 15ct are no longer available today in the UK.