9 Carat Gold vs 18 Carat Gold: What's the Difference?

16 September 2026 · Simon Goodburn

When you are shopping for jewellery, one of the first decisions you'll come across is whether to choose 9 carat or 18 carat gold. While they may look similar at first glance, there are some important differences in composition, colour and price.

Here's what you need to know.

What is 9 Carat Gold?

9 carat gold is made up of 37.5% pure gold, with the remaining 62.5% consisting of other metals such as silver and copper. These additional metals create a stronger, more durable alloy that stands up well to everyday wear.

Because it contains less pure gold, 9 carat gold has a slightly lighter yellow tone than higher-carat gold and is generally the more affordable option.

What is 18 Carat Gold?

18 carat gold contains 75% pure gold, with the remaining 25% made up of alloying metals like silver and copper.

The higher gold content gives 18 carat gold a richer colour, deeper lustre and a more luxurious appearance. It's often considered the premium choice for fine jewellery and heirloom pieces.

Is 18 Carat Gold Softer?

Technically, yes. But not in the way where you need to be concerned to wear it as you please!

Because 18 carat gold contains more pure gold, it is slightly softer than 9 carat gold. However, this doesn't mean it's too delicate for everyday wear.

The key consideration is how the jewellery will be worn.

Rings receive the most daily wear and are more likely to experience knocks and scratches. Most engagement rings are crafted in 18k Gold.
Necklaces, earrings and pendants generally experience much less impact, making the slight softness of 18 carat gold far less of a concern.

Many people assume that "softer" means fragile, but when well crafted, 18 carat jewellery is designed to last for generations.Why Does 18 Carat Gold Cost More?

The most obvious reason is its higher gold content, 18 carat gold contains twice as much pure gold as 9 carat gold.

However, there's another factor many people don't realise.

Gold is denser than the alloy metals used in 9 carat gold. This means that an 18 carat piece of the same size actually weighs more, requiring more material overall.

As a result, 18 carat jewellery is typically more than twice the price of an equivalent piece in 9 carat gold.

Is 18 Carat Better as an Heirloom?

Many jewellers would say yes.

Because it contains significantly more gold, 18 carat jewellery tends to retain greater intrinsic value over time. It's also commonly chosen for engagement rings and special pieces that are intended to be passed down through generations or remodelled in the future.

Is There Such a Thing as 27 Carat Gold?

No.

The highest purity of gold is 24 carat, which is 99.99% pure gold.

While 24 carat gold can be used to make jewellery, it isn't commonly used for gemstone settings because it's too soft to securely hold stones over time. That's why alloys like 18 carat and 9 carat are generally preferred—they offer a balance between beauty, durability and practicality.

There is also such an alloy as 22k. And this Jewellery is deeply saturated in tone, very recognisable and is extremely popular in certain cultures of around the world.

How Can You Tell if Your Jewellery is 9 or 18 Carat?

The easiest way is to look for the hallmark stamped inside the ring or on another discreet part of the jewellery.

Common hallmarks include:

375 = 9 carat gold (37.5% pure gold)
585 = 14 carat gold (58.5% pure gold)
750 = 18 carat gold (75% pure gold)

Some pieces may instead be stamped 9K, 14K, 18K or 22k or 24K, all of which indicate the gold purity.

Hallmarking is an important certification that verifies the alloy used and helps confirm the authenticity of the jewellery.

To the average eye, the luster and colour saturation of the gold will appear more yellow in 18k or higher alloy, 9k being lighter in tone.

And in some cases older heirloom jewellery may not include a hallmark, in that case we use a tool/machine to physically touch test the gold and it determines the alloy bracket.