What are the carats of gold? Difference between 18K, 14K and 9K?

February 17, 2021

Gold is one of the most precious and used metals in the world. We often hear about their carats, but what exactly do they represent?

What are carats?

First of all, it should be noted that, when we talk about carats, there are two types of measurements:

  • Gemology carats (ct) are a unit of mass used primarily to weigh gems and pearls.

  • Goldsmith 's carats (K or kt) designate the purity of the gold used in jewelry.

When we talk about gold we are referring to the second group and, therefore, its purity . Pure gold is made up of 24K or 1000 thousandths.

What is the difference between 18K, 14K and 9K gold?

Gold, at its highest purity, is too soft for the manufacture of jewelry pieces, so it is mixed with other metals. This process is known as alloying , and it serves to harden the gold and vary its color.

The mixture may contain a greater or lesser amount of gold compared to other metals. Depending on this quantity, there are pieces with more or less carats (K). For example, an 18K piece of jewelry means that it contains 18/24 parts gold, therefore, it is made up of 75% gold.

In the following table you can find different carats used in jewelry:








sterling gold




second grade gold





Why buy 18 karat gold if they are all gold?

First of all, it must be clear that the purchase of gold pieces represents a long-term investment. Not only because of the quality and durability of the material, but also because of its high market value, which will allow us to recover the initial investment if we decide to sell it later. In this sense, we will recover more money, the higher the percentage of gold.

Additionally, it must be taken into account that gold, unlike silver, does not oxidize. However, when alloying it with other materials, their characteristics begin to show if we increase their percentage and decrease that of pure gold. For example, a 14k or 9k piece has a high level of silver so the jewelry can oxidize.

Lastly, the shine and color of 18k gold is more beautiful to look at compared to lower karat gold.

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