All about gold: carats and karatsBy Simone Walsh
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 so expensive? What is a carat and a karat of gold and what's the difference? And why you should care 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. Don't forget to check out the gold jewellery for women in our online online jewellery shop.
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.
About precious metals
Learn more about gold and silver in these other handy articles:
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 often use sterling silver, gold vermeil or gold filled in our 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's highly unlikely to be gold at all.
What is a gold carat?
A carat - when used to refer to gold in Australia, the UK and elsewhere - is a measure of purity.
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 use 'ct'.
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' ... just to add to the confusion!
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.
Different carats of gold
24ct is pure gold: there is no higher carat for gold. It's generally considered to be too soft to make jewellery with on its own, however, it may be used for gilding, plating or for making ceremonial objects. It has a luminous, rich and warm golden colour. Given it's purity, 24ct gold is also the most expensive version of gold by weight.
22ct gold is 22 parts pure gold, making it 91.67% pure. The remainder can be made up of alloyed metals like zinc, copper, silver and nickel which are responsible for its enhanced strength. Gold jewellery made with 22ct metal is reliably durable, but it still retains much of the beautiful colour of 24ct gold, making it a good compromise. However, it's level of purity also makes it expensive.
18ct gold is of 75% gold and 25% other alloyed metal/s. In many countries, including Australia, this is the most commonly used purity of gold used in jewellery as it offers a very good compromise between price and purity (and excellent colour). It is regarded as the European standard purity of gold.
This caratage is commonly used in the United States and Simone Walsh Jewellery also uses it extensively in our solid gold jewellery designs. It's 58.3% pure gold, yet still retains a good gold colouring, making it a good compromise when cost is important.
9 or 10ct gold
These are generally the lowest carats of gold you will see as most countries regard lower purities as too low to be referred to as gold. 10ct is the minimum purity for gold in the United States, while 9ct is the minimum in Australia. These caratages are around 40% pure gold and are not as golden coloured as higher purities.
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 24ct gold by its very rich and warm golden colour. However, when you add copper, the resulting alloy is 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. Unplated white gold is more of a warm grey and is not widely used in jewellery.
There is no such thing as 24ct white gold: the highest carat for white gold will generally be 18ct or 20ct, but the higher the caratage the more yellow the colour will be.
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.
- How much gold is there in the world? - BBC News
- Gold - Wikipedia
- Colored Gold - Wikipedia
- White gold or rhodium plated - confusion or deception? - Finishing