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karats of gold

What Is The Karatage of Gold?

The use of gold in jewellery dates back thousands of years. Not to be confused with carats, a unit to measure the weight of a diamond or gemstone, or carrots the delicious orange vegetable. Karatage otherwise known as karats (K),  refers to the units of pure gold. In this article we explore what is the karatage of gold.


The word “karat” derives from the Arabic qīrāṭ, which originated from the Greek word kerátion meaning Carob seed. In Greek and Roman times it was used as a unit of weight however wasn’t used as a unit of weight for gold at the time. Over the years the use of gold was favoured more so to create jewellery pieces. During those years jewellers developed money saving tactics and increased durability by added base metals to the pure gold. Thus a karatage formula was created.

When gold is found within the earth it is in its purest form it is measured as 24k. For gold to be strong enough to hold diamonds a

nd gemstones, and withstand everyday wear and tear, additional metals are added to provide extra strength. Each type of gold eg white, yellow and rose include alternative amounts of base metals to provide its strength and colour.

Gold type

Base metals added

Yellow Gold

Gold, Zinc, Copper

White Gold

Gold, Nickel, Silver & Palladium 

Rose Gold

Gold, Copper & Silver.

The colour of each is determined by how much of the base metal is added. In rose gold if too much copper is added the redder the gold appears. Whereas in white gold it is the nickel and silver that give it its grey/white tone. Yellow gold with the added copper can make it appear brighter or duller yellow tone depending on the amount.

The karat of gold refers to how much units of gold is added. Each karat must be stamped or hallmarked as required by law onto a piece of jewellery. The only way to correctly know the gold karat is to refine it or drill a small hole and take a sample to test. The industry relies on the manufactures to correctly stamp the right K however it isn’t always the case.












The price differs greatly between 9k and 18k. This is due to the amount of pure gold used. As the table below shows 9k gold has only 37.5% of pure gold where as 18K includes 75%, making 18k more expensive product. In some countries around the world using 9k gold to manufacture is illegal as it contains less than 50% gold.


Pure gold

















Some might argue that 9k is stronger than 18k as it contains a higher percentage of base metals. Which is partly true however 9k is not as durable as 18k. An engagement ring made of 9k that is exposed to everyday wear and tear such as household cleaners, perspiration and perfumes will become duller in colour and tarnish quicker. On the other hand, when refining 18k the additional gold becomes what we call “work hardening” a process which causes the gold to harden. Making the refined product more durable to everyday wear and tear.


When creating a custom piece of jewellery, you must consider the durability and longevity of the piece. We always recommend using 18k gold for any custom piece. It’s strength and colour will compliment any piece and with a little maintenance, will look just as spectacular as the day you brought it for generations to come.