Understanding the Karat Value of Gold

When I buy gold from people, one of the most frequently-asked questions is:  “What is the difference between 24-karat and 14-karat gold?”

As I mentioned in my post What is the Difference between a Karat and a Carat? , a karat measures the purity of gold based on a scale of 1-24, with 24 karats being the purest. 

What this means is that 24-karat (24K) gold has 99.9% purity, generally referred to as “pure” gold. 

18-karat (18K) gold has 75% pure gold.  Its content is 18 parts gold and six parts other metal alloys.

14-karat (14K) gold has 58.3% pure gold.  Its content is 14 parts gold and ten parts other metal alloys.

10-karat (10K) gold has only 41.7% pure gold in it and is the lowest purity that is still considered gold.  Its content is 10 parts gold and 14 parts other metal alloys.

You can figure out these percentages of purity by dividing the number of karats by 24; for example, 14 divided by 24 equals 0.583 or 58.3%.   

Why are there sometimes three numbers instead of the number of karats?

Internationally, you will also see three digits instead of karats stamped on jewelry which let you know the level of gold purity.  This is called the millesimal fineness system.  It indicates the purity of platinum, gold, and silver by parts per thousand of pure metal by mass in the alloy.

Or to state it more simply:

24K = 99.9% purity = 999 (also known as “three nines fine”)

18K = 75% purity = 750

14K = 58.3% purity = 585

10K = 41.7% purity = 417

2 Comments on Understanding the Karat Value of Gold

What is the Difference between a Karat and a Carat? | Gemologist Sam


[...] We’ll discuss in more detail about the difference between 24 karats and other levels of karats, as well as the international system in the next post, Understanding the Karat Value of Gold. [...]

How to Test Gold at Home or When Traveling | Gemologist Sam


[...] previous blog posts, you have learned the difference between a karat and a carat as well as understanding the karat value of gold.  But how can you test gold to find out if it’s real or not?  And how can you be sure the karat [...]

Tell me what you're thinking...
and oh, if you want a pic to show with your comment, go get a gravatar!