9K Gold and 18K Gold – What is the difference?

What is the difference between 9K and 18K gold? In the UK, jewellers tend to sell gold in these two purities. But what do they mean, and which is better? In our guide below we explain the differences in appearance, quality and price – so you can shop gold jewellery with confidence.

What are gold karats?

karat is a unit of gold purity. It refers to the amount of pure gold there is in a piece of jewellery.

The abbreviation for karats is the letter K.

How do karat measurements work?

One karat represents 1/24th of the whole gold content in a piece of jewellery.

So at the top of the scale, 24K gold is 100% pure gold.

And, for example, 9K gold contains 37.5% pure gold, the rest being a mix of alloy metals.

What is the difference between 9K and 18K gold
A pure gold bar, image Credit Wikipedia Commons by Realterm

What other gold purities are there?

Gold items come in various purities, as follows:

  • 9K gold is 37.5% pure gold
  • 14K gold is 58.3% pure gold
  • 18K gold is 75% pure gold
  • 22K gold is 91.6% pure gold
  • 24K gold is 100% pure gold
What is the difference between 9K and 18K gold
The process of melting gold

Why is gold mixed with other metals? Why not use pure gold?

Gold is a very soft metal and bends easily.

That’s why, on its own, pure gold is not ideal for jewellery items. Imagine your gold ring bending out of shape whenever you wear it.

For use in jewellery, gold has to be mixed with harder metals to give it strength and shape.

What is the difference between 9K and 18K gold
A white gold ring being made by TheDiamondStore | Watch video

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

The main difference is the gold content. 9K gold contains only 37.5% pure gold, while 18K gold contains 75% pure gold.

The second difference is the price. 9K gold contains more alloy metals than gold. Therefore, it is less expensive than 18K gold which contains more gold than alloy metals.

Finally, you have to consider quality and value. 18K gold feels heavier and more substantial and luxurious to the touch than 9K gold does. Also, 18K gold items have more long-term and re-sale value than 9K gold.

A 9K gold ring and 18K gold ring

What metals are mixed with gold?

Gold can be alloyed with various other metals to give it strength and shape.

Common alloy metals include silver, copper, platinum, palladium and zinc.

Alloy metals can also be used to change the colour of gold. For example, copper gives rose gold its reddish hue.

Colour – is there a difference between 9K and 18K gold?

With yellow gold, 18K gold may look richer and more yellow than 9K gold when compared side by side.

The same applies to rose gold; its golden-red colour may look slightly more intense in 18K purity when compared to 9K purity.

When it comes to white gold, you cannot really see the difference. That’s because white gold is alloyed with white metals like silver and coated in rhodium to make it look silvery-white.

What is the difference between 9K and 18K gold

How is white and rose gold purity measured?

The purity of white gold and rose gold is measured in karats, exactly the same as yellow gold.

Read our articles to learn more about white gold and rose gold.

The same ring in 9K yellow gold, 9K white gold and 9K rose gold

A note about platinum

It’s also important to note the difference between 18K white gold and platinum when you’re choosing a suitable metal for your jewellery.

Platinum is a silvery-white metal that’s extremely long-wearing, and therefore, ideal for engagement rings. Learn more about platinum.

What is the difference between 9K and 18K gold

How do I know the purity of my gold jewellery?

In the UK, jewellery cannot be sold as gold unless it has been tested and verified by an official UK Government regulated Assay Office.

The Assay Office stamps the gold item with a hallmark, so you know what purity you’re buying.

Watch our video or read our article to learn more about hallmarking.

What is the difference between 9K and 18K gold
A gold ring is stamped with a hallmark at an Assay Office

FINAL VERDICT: What is the difference between 9K and 18K gold? Which is better for you?

The choice between 9K gold and 18K depends on your budget, and how you want your jewellery to feel, perform and maintain value:

Buy 18K gold when…

Buy 9K gold when…

  • You’re looking for something in an affordable price range
  • You’re not concerned about long-term or re-sale value
  • You want an item of fashion jewellery that you’re planning to wear occasionally