What is the Difference between a Karat and a Carat?

I buy gold and jewelry from a lot of people every day, and a common question that I’m asked is, “What is the difference between a Karat and a Carat?”  It can be a little confusing, especially since they are both pronounced “carrot”!

Well there IS a difference between “karat” and “carat” … usually.  Let me clarify.



A karat measures the purity of gold based on a scale of 1-24, with 24 karats being the purest.  And actually, below 10 karats isn’t even considered gold.  In jewelry, you will often find the karat weight stamped on a clasp or inside a ring.  It is frequently abbreviated as 18K.

Gold is a very soft metal, so it is fortified with alloys (a harder metal, such as copper, zinc, or nickel) to make it stronger.  24-karat gold has the least percentage of alloys, whereas 12-karat gold is only 50% pure, for example.

The United States and Canada use the word karat with a “K” whereas in other countries they might use a “C” or simply use the millesimal fineness system instead.

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.

But right now, it’s time to understand what Carat means.



A carat measures the mass of gemstones and pearls when weighing them, which is why you have a one-carat diamond (1ct) in your 18-karat (18k) gold ring. 

The word carat is derived from carob beans which had such a consistent weight that gemstones were measured against it for a very long time.   However, in 1907, the carat became the legal standard for weighing precious gems. 

The global standard is:  one carat = 200 milligrams.  It is based on the metric system.  For example, if your diamond weighs one gram, it would be five carats.  Below one carat in weight, it will be referred to as a fraction, such as a “quarter of a carat.”

A carat can be divided into 100 points.  So, for example, a half-carat stone (0.50ct) can be called a “fifty pointer.”


I hope you found this introduction to Karat versus Carat helpful.  Let me know what you think; or ask me a question!


3 Comments on What is the Difference between a Karat and a Carat?

    [...] 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 [...]

    [...] 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 [...]

    [...] is a Diamond’s Carat Weight? The first of the four Cs is “carat.”  The carat weight measures the mass of a diamond.  One carat is defined as 200 milligrams (about 0.007 ounce [...]

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

      The charts below are updated frequently. Refresh your screen every 10-12 minutes to see the current gold and platinum prices.

      [Most Recent Quotes from www.kitco.com] [Most Recent Quotes from www.kitco.com]

    • Contact Sam Today!

      Gemologist Sam makes house calls or you can meet with him at his office. Either way, it's by appointment only!

      Call Sam at 727-804-7463.

      E-mail him at Sam@GemologistSam.com.

      His office is located at: 5510 River Road, Suite #211; New Port Richey, FL 34652.

  • Categories

  • Testimonials

    Read testimonials, ask questions, and rave about Gemologist Sam on his Feedback page!