Should I buy 9 karat or 18 karat gold?

May 22 2023

If you’re thinking about buying any kind of gold jewellery, especially gold wedding rings, you’re bound to run into this karat conundrum. Read on to find out what the difference is and why it should matter to you.

What is a karat?

Because we sell both diamonds and gold, we often confuse people by talking about carats-with-a-c and karats-with-a-k. Although they sound exactly the same, the two words are very different.

karat n.

a unit for measuring the purity of gold

carat n.

a unit of weight in gemstones, e.g. diamonds

Of course, neither one should be confused with:

carrot n.

a pointy orange vegetable, used for making casseroles and snowmen

Yes, okay, but what does ‘karat’ mean?

Gold is a soft metal. It’s often combined with other metals to make it stronger. So, rather bizarrely, karats tell you how much actual gold is in your gold.

Gold is described as being made up of 24 parts, or ‘karats’. So 24 karat gold is 100% pure gold with no added ingredients.

18 karat gold is actually a gold alloy made up of 18 parts gold (75%) and 6 parts silver and/or copper, nickel and zinc.

And, yes, you've guessed it, 9 karat gold contains 9 parts of gold for every 15 parts of other stuff. That means 9-karat gold is only 37.5% gold. (Interesting factoid: in the US, it’s illegal to refer to anything less than 10 karats as gold.)

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Does that mean 24-karat gold is best?

Yes and no.

24-karat gold is the purest form of gold. Pure gold - or usually, ‘near pure’ 22-karat gold – is highly prized in many parts of the world. Because it’s so soft, it’s easy to shape into delicate and intricate jewellery.

However, 24-karat gold isn't very durable. It is also very expensive. A 24-karat gold wedding ring would not only cost a lot but it would get bashed up pretty fast. Hence the demand for 9-karat and 18-karat gold alloys.

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So what should I buy?

The simple answer? 18 karat.

18 karat gold is purer and, well, more gold than 9 karats, so it’s always best to opt for 18 karats if you can. It doesn't tarnish, it’s more durable and because it costs more, it’ll be worth more in the long run.

Conversely, 9-karat gold contains a higher proportion of other metals so it will tarnish over time. Depending on which metals are used to make the alloy, it’s also much more likely to cause a skin reaction in some people.

That said there are reasons to opt for 9-karat gold. It’s a popular choice for men’s wedding bands and it’s also perfect if you’re on a budget. And if you look after it and clean it often, it’s certainly going to last and look beautiful as long as you do.

But there’s simply no substitute for the rich, luxurious feel of 18-karat gold. In fact, when it comes to beautiful, wearable jewellery, 18-karat gold is the very definition of gold.

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So what about 18K White gold and 18K Rose Gold?  

The purity of White Gold and Rose Gold is also measured in karats, the same way as Yellow Gold. 

The main difference is the more Copper used, the redder the metal helping Rose Gold with its Rosey and White Gold is mixed with light metals such as nickel. Meaning neither metal can be 100% pure. 

Find out more about different types of metal here. 

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