Guide to gold purity: 24k, 22k, and 18k differences

Online searches could also be confusing, especially when encountering words like ‘carat’ and ‘karat’. So, how do you know the best gold based on purity or colour? We have created this post just for that! In it, you’ll learn the different karats of gold, the various shades of gold, and how to measure the purity of gold using finesses. 

But before we dive into these concepts, let’s first look at the difference between ‘carat’ and ‘karat’.

What’s the difference between a ‘carat’ vs ‘karat’?

Although both are forms of measurement in the jewellery world, these two terms are different in meaning. ‘Carat’ as a unit of measurement refers to the weight and size of gemstones like diamonds. On the other hand, ‘karat’ is a term used to measure purity in gold. 

Which are the different karats of gold?

As mentioned above, the karat helps in measuring the purity or content of gold. The system measures the ratio of gold to other alloys or metals in a piece of gold. The purity of gold is marked on a scale of 0 to 24, with the former being the least pure and the latter being the most refined.

The least gold purity measure for a piece of jewellery varies depending on countries. For instance, this value is 10k in the U.S, 9k in the U.K., and 8k in Denmark. So, what's the difference between 24k, 22k, 18k, and other karats of gold? Below is a guide that explains the difference between these karats of gold.

24k gold

With a 99.99% purity, 24 karat gold is the purest form of gold there is. This gold has no traces of other metals or alloys. You can differentiate this gold from the different karats by its unique bright yellow colour. 

The 24k gold is soft and easily pliable, mainly because of its lower density. Thus, it can’t be used to make jewellery. Instead, it is used to make gold bars and coins, and other medical and electronic devices. 

22k gold

22k means that there are 22 out of 24 parts of gold in the metal. The remaining two parts are made of other alloys, making the gold harder and more durable than the 24k gold. As such, 22k gold is used to make regular jewellery and other ornaments. 

However, the 22 karats aren't ideal for making heavy studded gold jewellery. This is because gold can barely hold the weight of gemstones like diamonds through daily use. As such, this form of gold is used to make jewellery that people wear occasionally. 

18k gold

18 karat gold contains 18 parts of pure gold, and the rest are nickel, zinc, copper, silver, or other metals. In other words, 18k comprises 75% pure gold and 25% of other metals.

This form of gold is suitable for making diamond and studded jewellery – jewellery that you can wear daily. It has a yellow tone with a slight dull shade, making it appealing and desirable for making jewellery. 

Note: There are other forms of gold based on purity, including 14k, 19k, 12k, 21k, 10k, 1k etc. 

What is the fineness, and how’s it calculated? 

Fineness is yet another way of expressing the purity of gold – usually used in the West. Parts per thousand of genuine gold by mass in an alloy are used to indicate it. For instance, 18k is expressed as 18 divided by 24, multiplied by 1000, giving you a fineness of 0.75.

With the many varieties of gold forms in the market, choosing the best quality of gold jewellery could be challenging. If you aren’t keen, you can easily spend your money on fake jewellery or ornaments. Essentially, anything with less than 37.5% of gold is regarded as fake in the U.K. 

Get in touch

Here at Cuttings, we are a family-run independent jeweller owned by the Kirkland family for over 50 years and we are here to help you with your jewellery investment. Whether you are looking to purchase a timeless gold or diamond piece, or if you are looking to get your jewellery valued with our pawnbroking team, we are here to help. We have expert knowledge and provide expert advice so please get in touch with us here.