What is the difference between 9ct and 18ct gold?

In Australia, gold most commonly comes in two purities – 9ct and 18ct. So when it comes to custom making or purchasing a piece of jewellery, our team always get asked what is the difference between the two?

So we are here to help you understand how 9ct varies from 18ct, and guide you to making the best choice for your needs.

The main difference is the precious metal content, essentially how much pure gold each carat has. This chart from PWBeck shows the different percentages. 9ct gold contains 37.5% pure gold. 18ct gold contains 75% pure gold.

The remainder is an alloy of other metals. The other metals are dependant on the colour of gold. So as an example, rose gold will have a higher copper content in the alloy metals, where as white gold may include silver, palladium or platinum.

Which is more expensive 18ct or 9ct gold?

An 18ct gold piece is more expensive than a 9ct gold piece of the same weight, due to it containing twice as much pure gold.

Is 9ct or 18ct gold better?

This totally depends on what you require from the piece. 18ct gold is more durable and longer lasting. However 9ct gold can be still be a great choice in some situations, consider these points when choosing which carat gold:

If it is a piece you wear frequently, like an engagement ring or wedding band, 18ct gold would be the best option for the durability and longevity. It also generally will have a richer colour. This is also the best choice when creating an heirloom piece.

However if you are looking for something in a lower price bracket or a dress piece that is worn less regularly, then 9ct gold is great option. Some people prefer the paler colouring of 9ct against their skin tone.

The durability of a piece can also come down to the design and structure of a piece, more so than the metal used. So when designing a piece that is planned to be worn regularly, make sure the piece is made to suit how it will be worn. This can come down to the style of setting, setting thickness and band thickness.

How to choose which carat to use?

So the three main things to consider when choosing which metal is best for you are:

Durability: How much wear does your jewellery get and how long does it need to last?

Expense: What is your budget?

Colour: What do you want your metal to look like?

We quite happily make custom pieces including engagement rings in both 18ct or 9ct gold. At the end of the day it comes down to what is best for your situation

The verdict – 9ct gold or 18ct gold?

If you’re looking for a long-lasting piece, and your budget allows 18ct gold will give you more longevity and durability. If you are just shopping for a dress piece and after a lower price point, 9ct gold can be a great choice.

A good point to remember is that the design and quality of how your piece is made can have more of an impact on its durability than what metal it’s made in

Other Carats of gold

As you have already seen, the most common carats of gold you’ll find in Australia are 18ct and 9ct gold. There are other purities such as 22ct, 14ct and 10ct that you will find from other countries.

We use the term Carat (ct), or in other counrtires, karat (k), to indicate the purity of the metal. Pure gold is when the metal is 24ct. Pure gold is too soft to use so therefore is alloyed with other metals to increase its hardness.

9ct gold – 37.5% pure gold hallmarked with 375

10ct gold – 41.7% pure gold hallmarked with 417

14ct gold – 58.5% pure gold hallmarked with 585

18ct gold – 75% pure gold hallmarks with 750

22ct gold – 91.6% pure gold hallmarked with 916

Now you are armed with all the information you need to make the best choice for your next jewellery purchase!

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