Gold has historically been one of the most popular (and most expensive) precious metals on the planet. But you might wonder: What is it about gold? Why is it so popular? And why is it so very expensive? What is a carat and a karat of gold and is there a difference? And why should you care about it anyway?

We're here to give you the inside scoop on this truly beautiful precious metal and provide you with some interesting facts about gold. This will help you to be better informed and make better choices when shopping for jewellery.

Don't forget to check out the gold jewellery for women in our Australian online jewellery shop. In particular take a look at our real solid gold jewellery pieces.

Let's get started ...

Gold: the lowdown

Pure gold is incredibly durable. It's the most non-reactive of all metals: it won't react with oxygen or most chemicals, meaning it won't tarnish, rust or perish. This makes it perfect for use in jewellery and high status objects which are intended to retain their value and finish indefinitely.

It's also very pure in the form in which it's found naturally, unlike many other metals which can be difficult to extract from their ores.

As a result humans have been working with it for a very long time: gold is one of the metals of antiquity (the others being gold, silver, copper, tin, lead, iron and mercury) which were used by prehistoric humans. While we don't know the origins of its early discovery and use, we do have evidence of the Egyptians using gold as far back as 3000 BC.

Gold is also a very workable metal, which is another reason jewellers and goldsmiths love to use it in their designs.

Plus it's also a truly beautiful metal, displaying a broad spectrum of colours depending on how it is alloyed with other metals. The purest gold at (24 carat gold) is a luminous, rich and warm colour, unmatched by any other metals.

Finally, gold is relatively rare and often difficult to extract in large quantities, making it particularly precious (and therefore expensive). It's estimated that only 171,300 tonnes of gold have ever been mined globally: about enough to fit into a single Olympic sized swimming pool.

So how expensive is gold?

The short answer is: very! At the time of writing this article gold is 75 times more expensive than silver. This is the reason why we may use sterling silver, gold vermeil or gold filled in our gold jewellery designs, while only making small pieces or highlights with solid gold.

There truly is no such thing as cheap gold jewellery: don't let anybody tell you otherwise. If you've got some inexpensive gold jewellery and it keeps turning your skin green or black, then it may not be gold at all. Learn more about how to care for and clean gold jewellery.

What is a gold carat?

A carat - when used to refer to gold in Australia, the UK and elsewhere - is a measure of purity. Read below to find out about what a 'karat' is.

The purest gold is 24 carats, but when it comes to making useable objects and gold jewellery, 24ct gold is generally considered too soft. This is why gold is often alloyed with a metal like copper or silver which makes it harder and better to work with and wear. This alloying process reduces the purity, but makes the gold more useable.

A single gold carat is 1 part of a possible 24. So 18 carat gold is an alloy of 18 parts pure gold and 6 parts of another metal (most often copper). So 9 carat gold has 9 parts gold plus 15 parts of another metal.

You'll also see the word 'carat' used in relation to gemstones, in which case it's a measure of mass rather than purity.

What is a gold karat?

A 'gold karat' is exactly the same thing as a 'gold carat': the difference is simply that in US English the word is spelled with a K instead of a C. And in the US you'll see '24K' used to indicate purity rather than '24ct' as in other countries. As we're in Australia we tend to use 'ct' when referring to gold, but the meaning is the same and the values used are identical.

The English have been spelling the word as 'carat' since around 1300 and this is the spelling that continues to be used in the UK, Australia and other countries.

When it comes to gemstone mass, US English spells the word as 'carat', as it is also spelled in standard English ... just to add to the confusion!

Gold hallmarks

The different purities of gold are usually identified by a hallmark (or stamp) with the number of carats accompanied by a letter or letters.

For example, depending on where your jewellery was made and the stamps available to the maker, for 18 carat gold you'll most commonly see: 18, 18ct, 18kt or 18k marked on the metal. 

What are the different carats of gold?

What is 9ct gold?

9ct gold (or 9k gold) is the minimum purity level allowed to be sold as gold in Australia. You may see it stamped with the numbers for 375, which means it contains 37.5% pure gold. In many other countries the lowest purity level is 10ct.

These lower carat golds are also the dullest coloured when it comes to yellow and rose golds as they contain the least amount of pure gold content. So is 9ct gold any good? Well it is generally affordable as far as gold goes and it will wear quite well, but it's not very eye-catching or particularly valuable. We recommend going for a higher caratage if you can afford it.

What is 14ct gold?

14ct gold (or 14k gold) has a higher level of gold purity than the lowest 9 or 10ct golds and also has a much better colour, but without having the very high price tag of 18ct or 22ct gold. With 58.5% pure gold, you'll sometimes see this type of gold stamped with the numbers 585.

We think 14ct gold is a good compromise between colour, preciousness and affordability, which is why we tend to use it in our solid gold jewellery designs.. It has been widely used in the USA for a long time. It has only fairly recently become more standard in Australia and other countries, where 18ct gold was usually the next step up available from the minimum of 9ct gold.

What is 18ct gold?

18ct gold (or 18k gold) has historically been the most commonly used type of gold in higher value jewellery in Australia. It's the most commonly used carat of gold used in wedding and engagement rings. It's made of 75% pure gold. It has a vibrant colour and wears beautifully, but it is expensive and the extra amount of pure gold does cause a noticeable jump in price from 14ct gold.

What is 22ct gold?

22ct gold (or 22k gold) is 91.6% pure gold. It's a very expensive metal which has a very vibrant colour, but the downside is that it's also very soft. This makes it poorly suited to a lot of uses in jewellery and you're less likely to see it made into rings, chains, etc. which need to take a lot of wear and tear. If you see it in jewellery form at all, it will generally be for smaller pieces that are not often worn.

What is 24ct gold?

24ct gold (or 24k gold) is 99.9% pure gold: the most pure form of gold you are likely to find and also the most expensive. However, it is very soft and is almost never used in jewellery, other than in plating or gilding where fine layers are deposited over another metal. 24ct gold is generally seen in gold bars used as an investment.

Different colours of gold

You've probably seen a variety of gold colours when looking at jewellery. The variations are all down to alloying with other metals.

You can identify higher purities of yellow gold by their rich and warm golden colour. However, when you alloy it with more copper, the resulting metal is more pink coloured and is known as rose gold, red gold or pink gold.

White gold includes a substantial amount of nickel, manganese or palladium. The white gold jewellery you will see in jewellery shops is almost always plated with rhodium, giving it a bright white colour and you should be aware that this plating is likely to need replacing as it will wear off over time. Unplated white gold is more of a warm grey and is not widely used in jewellery.

There are also other colours of gold which are more rarely seen in jewellery designs: purple, blue, black and green are some types. All of them are the result of pure gold being alloyed with other metal to change the colouring.

There is no such thing as 24ct gold which is not yellow: the highest carat for coloured golds will generally be 18ct or 20ct, but the higher the caratage the more yellow the colour will be.

(Reading this on a website that isn't simonewalsh.com? Be aware that the content has been stolen, infringing the copyright of a small business. ABN: 65108844126)

The parting shot

Gold jewellery, especially in its purer forms, is truly exquisite and I think everybody needs some of it in their jewellery collection.

With some care your jewellery made in gold will retain its good looks and value for longer than any of us will be around. Not only will you be able to hand your gold jewellery down to future generations, but you'll look great wearing it in the interim. What's not to love?

Check out our gold necklaces, gold rings and gold earrings.

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Related links:

• How much gold is there in the world? - BBC News
• Gold - Wikipedia
• Colored Gold - Wikipedia
• White gold or rhodium plated - confusion or deception? - Finishing
• About Gold Jewellery - World Gold Council