18 Carat Yellow Gold
In its pure form, gold is 24 carat and has a distinct, intense yellow colour. 18 carat yellow gold is represented by the ‘750’ hallmark signifying a pure gold content of 75%. Similarly, 14 carat is ‘585’ with 58.5% pure gold content, and 9 carat ‘375’ has 37.5%.
By mixing it with a variety of other metals such as copper and silver, the concentration of pure gold is reduced to achieve a lower carat. This process is known as alloying. As the carat value drops, so does the intensity of the yellow colour. 18 carat yellow gold will have a stronger tinge of yellow than the paler 9 carat yellow gold.
The lower carats such as 9 carat can at times react with certain skin types. The type of metal used in the alloy can also greatly affect this reaction.
18 carat yellow gold is widely used in jewellery due to its rich colour, malleability and nobleness (less likelihood of reacting with the skin). It is often believed that 9 carat is a stronger metal than 18 carat. The higher pure gold content in 18 carat will make it more malleable than 9 carat, but that does not necessarily impact the longevity of the metal.