Understanding 9ct, 14ct, 18ct and 24ct gold.
When selecting gold for your jewellery, it's important to consider not only the carat rating but also factors like hardness, alloy composition, and how to care for each type to prevent tarnishing. Here’s a comparison of 9ct, 14ct, 18ct, and 24ct gold.
9ct Gold - 375
9ct gold is made up of 37.5% pure gold and 62.5% other metals such as copper, silver, zinc, or palladium. This makes it the hardest of the four options, resistant to scratching, bending, and wear. Due to the higher alloy content, 9ct gold is more prone to tarnishing and discolouration over time, especially in contact with moisture, chemicals, or skin oils. 9ct gold an excellent choice for everyday jewellery and the most affordable option. It is the lowest purity of gold legally available in New Zealand.
14ct Gold - 585
14ct gold contains 58.5% pure gold and 41.5% alloy metals such as copper, silver, and zinc. This balance provides a good mix of durability richness in colour. 14ct gold has moderate hardness and tensile strength, offering a good compromise between durability and flexibility. This makes 14ct gold an ideal when considering durability, colour and value. While 14ct gold is less prone to tarnishing than 9ct, it can still discolour if exposed to harsh environments or chemicals.
18ct Gold - 750
18ct gold is composed of 75% pure gold and 25% other metals like copper, silver, zinc, or palladium. The higher gold content gives it a richer colour and higher value making it the most popular for fine jewellery. 18ct gold is softer, making it less scratch resistant than the lower carat golds but is the most desired carat in high end jewellery, with 22 and 24 carat golds being too soft for frequent wear. 18ct gold is less likely to tarnish compared to lower carat gold due to its higher gold content. However, it can still develop a patina over time.
24ct Gold - 999
24ct gold is nearly pure, containing 99.9% gold with very little or no alloy metals. 24ct gold has the lowest tensile strength and is the softest of all gold types. It is extremely malleable and can bend, scratch, and lose shape easily, making it unsuitable for jewellery that will be worn frequently. Its softness and low tensile strength mean it’s best reserved for ornamental pieces or jewellery that is not subject to stress or impact. Pure gold (24ct) does not tarnish, but it can still be affected by dirt, dust, and oils, which can dull its shine over time.
Summary of Tarnishing and Care
9ct Gold: Most durable and affordable but more prone to tarnishing and of lesser value.
14ct Gold: Good balance of durability, tarnish resistance and affordability while having a higher concentration of pure gold than other metals.
18ct Gold: Less prone to tarnishing, of high value but softer, requiring more care than the lower carat golds.
24ct Gold: Does not tarnish but is very soft and needs careful handling and storage to prevent damage.
By understanding the differences in hardness, alloy composition, and how each type of gold reacts to wear and environmental factors, you can choose the gold that best fits your lifestyle and ensure it stays beautiful for years to come.