9ct Gold vs 18ct Gold

One of the most common questions we receive from couples planning their custom engagement or wedding rings is "What is the difference between 9ct and 18ct gold?" This guide will walk you through the main characteristics that set them apart.

You may be wondering what exactly ‘ct’ or sometimes seen as ‘K’, refers to. The ‘carat’ of a metal denotes the percentage of pure gold in the alloy, with 9ct being 37.5% and 18ct 75% pure gold.

Gold in its purest form is too soft to be used in fine jewellery, so it is commonly mixed with other metals to increase its strength and durability, as well as to create unique colours like Rose Gold and White Gold

Metal Alloys

When it comes to the metal alloys found in 9ct and 18ct gold, the differences primarily lie in their composition.

Gold purity is measured in carats (ct), with 24ct being pure gold. 9ct and 18ct gold are gold alloys, meaning they are mixed with other metals to enhance strength, durability, and alter color.

9ct Gold (37.5% Pure Gold)

Yellow Gold: 37.5% gold, mixed with copper and silver in roughly equal proportions to maintain a warm yellow tone.
Rose Gold: 37.5% gold, with a higher percentage of copper and a smaller amount of silver, giving it a reddish-pink hue.
White Gold: 37.5% gold, alloyed with palladium, nickel, or zinc to create a silvery-white appearance, often plated with rhodium for enhanced whiteness.

18ct Gold (75% Pure Gold)

Yellow Gold: 75% gold, blended with 25% copper and silver to achieve a rich, classic yellow color.
Rose Gold: 75% gold, with a higher ratio of copper to silver, resulting in a deeper rose or pink tone.
White Gold: 75% gold, mixed with palladium, nickel, or other white metals, and typically rhodium-plated for a bright, reflective finish.

The color intensity and durability of these alloys depend on the specific metal mix, with 18ct gold being more vibrant due to its higher gold content, while 9ct gold is more durable because of the larger proportion of other metals.

Metal Colours

The colour variations in gold metals occur due to the specific alloys used in the mixture. When pure gold is combined with other metals, it not only strengthens the material but also affects its hue. For example, adding copper creates a warm, pinkish tone known as Rose Gold, while mixing gold with palladium or nickel results in the cooler, silvery finish of White Gold. Each metal contributes its unique traits, affecting both the appearance and properties of the final product, allowing for a range of beautiful colours to suit individual preferences.

Durability and Tarnish

9ct gold consists of a higher proportion of non-precious metals, with 62.5% compared to 18ct gold, which contains 75% pure gold. Many people mistakenly think that this makes 9ct gold more durable for everyday use, but that's incorrect. The extra metals in 9ct gold actually lower its density, causing it to wear down faster. On the other hand, 18ct gold not only boasts greater durability and resistance to wear but is also less prone to tarnishing due to its significantly higher gold content. This makes 18ct gold a superior choice for daily wear.

9ct Gold

Not as dense and tend to wear over time.

18ct gold ✅

Better withstands impacts and endures through daily use, and is less prone to tarnish

9ct vs 18ct Summary

When comparing 18ct gold and 9ct gold, 18ct is definitely worth considering due to its higher price, which is justified by its greater gold content, resulting in superior durability and performance. While 9ct can be a good choice for occasional jewellery items, such as dress rings and earrings, 18ct is better suited for everyday pieces, like engagement and wedding rings.

It’s important to differentiate between 18ct white gold and platinum. Platinum is a denser, nearly pure white metal (95%) known for its long-lasting durability, making it ideal for intricate engagement ring settings. Unlike white gold, platinum doesn’t require rhodium plating as it maintains its natural colour. However, platinum typically comes at a higher price than 18ct gold.