What Are the Differences Between 9-Karat and 18-Karat Gold?


Because of the softness of pure gold (24-Karat), it is usually alloyed with base metals for use in jewelry, altering its hardness and ductility or color.

18-karat gold is an alloy often used in jewelry, but what about 9-karat gold? How do these two types of gold compare, and what are the differences between them?

What is 9K Gold?

9-karat gold contains 9 parts pure gold and 15 parts additional metals such as silver, tin, nickel, zinc, palladium, etc.

Calculated as a percentage, the purity of a 9K alloy is 37.5% ­­ – this is the proportion of pure gold it contains. Now you understand why 9K gold is stamped with the number 375, it indicates the percentage of pure gold for this alloy.

What is 18K Gold?

18-karat gold contains 18 parts pure gold per 24 parts alloy in total. Therefore, its gold purity is 75% (stamped 750).

Because of its relatively high purity and good durability, 18K gold is one of the most popular alloys used in jewelry.

How Are 9K and 18K Gold Different?

As we already saw earlier, 9-karat and 18-karat gold differ greatly in terms of purity.

The other most important differences, which stem from the difference in purity, are in the price, durability, and color of 9K and 18K pieces.

Price and Affordability

The difference in purity between 9K and 18K gold also leads to a difference in price. Since 9-karat jewelry contains less gold, it is cheaper per gram. 18K gold is significantly more expensive.


Alloys with a higher gold content will have a color that is more saturated and yellow. In contrast, lower-karat alloys will look paler in comparison.

Compared with 9K pieces, 18K jewelry tends to have a richer color. So, if you are looking for jewelry that looks more like pure gold, 18 karats is the way to go.

9K jewelry is a recommended choice only if you don’t care about a lighter yellow color and if you put greater importance on price and affordability.


Pure gold does not tarnish and lasts forever, but the other metals in the alloy will tarnish. 18 karat gold tends to retain it’s shiny yellow look. However 9 carat gold is more vulnerable to tarnishing, and sometimes has to be cleaned with a silver polish clothe.

Ann SchaublinComment