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What are the different types of gold and which is best? A short guide to colours, carats and more…

Whether used for handmade jewellery, decorative goods or currency, gold has been highly prized for centuries both for its colour and its rarity. However, not all gold is created equal. While many people assume that all gold is the same, there are actually significant differences between the various carats of gold. Understanding these differences is essential if you are planning to purchase gold jewellery or other items. In this blog post, I will explore the differences between the different carats of gold so that you have the information you need to make an informed decision when it comes to buying gold.

Above: Circle triangle earrings in solid 9ct gold with tube set diamonds by Elin Horgan Jewellery

How do I know which type of gold I’m buying?

The amount of gold in a piece of jewellery is measured in carats (ct) in the UK or karats (k) in the US, with 24ct being pure gold. 24ct gold is too soft to be used as it is and so it is alloyed with other materials to make it stronger and more hard wearing. So, if a piece of jewellery is marked as 18ct gold, it means that 18 out of 24 parts of the metal are gold, or it is 75% pure.

In the UK, any gold jewellery weighing 1g or over has to be hallmarked at one of the four Assay Offices in London, Birmingham, Sheffield and Edinburgh. Hallmarking shows that the piece has been independently tested and meets the legal standards of purity. Hallmarks are usually pretty small so you may need magnification to be able to read it properly on your piece of jewellery.

The Millesimal Fineness Mark for gold appears in an octagonal box showing the purity of the metal as parts per thousand. So 375 = 9ct gold (37.5% pure); 585 = 14ct gold (58.5% pure); 750 =18ct gold (75% pure) and 916 = 22ct gold (91.6% pure). However, do be aware that vintage jewellery made some time ago may show the caratage simply written as a number eg:- 18 or 22.

Above: remodelled 18ct gold and diamond circle earrings, handmade by Elin Horgan Jewellery

What is the difference between 9ct, 18ct and 22ct gold?

9ct gold jewellery is a type of gold jewellery that is commonly used in everyday wear. It is made up of 37.5% pure gold and a combination of other metals such as copper, silver, or zinc, which are added to make the gold more durable and affordable. This type of gold is popular because it is more affordable than higher carat gold, yet still has the lustrous shine and color of gold (albeit quite a pale straw-like shade) The use of other metals in its composition also makes it more durable and resistant to wear and tear, making it ideal for everyday wear.