What Is a Karat? Why Are There Also Carats?

(Last Updated On: April 24, 2022)

Before you knew anything about jewelry someone probably once threw out “24-karat gold” as a way to say something was valuable. If you heard the phrase used before you actually knew what a karat was, you might have been wondering why someone had a bracelet made of 24 carrots. Maybe that was just us in elementary school, in which case… completely disregard–we always knew exactly what a karat was and were just born with that innate knowledge. Definitely. Anyway, what the heck is a karat anyway?

Carats and Karats (Also, carrots)

The last one isn’t really related to anything we’re discussing today, since a carrot is a vegetable. Not too much to explain there, except the fact that carrots give you super-eyes is actually WWII propaganda.

Let’s go in order, starting with the carats. Big picture, carats are for diamonds and karats are for gold. They also both measure completely different things. Carats, abbreviated ct, are a measure of mass. One carat is equal to exactly 200 milligrams, and it’s used to measure gemstones or pearls (particularly diamonds, if you’re shopping for an engagement ring). For those who want to turn that into dollars, it’s anywhere between \$2,500 and \$18,000. In ounces, one carat is 0.00705. This conception of the carat was adopted in 1907. Carats are often divided into 100 points, where one point is 2 milligrams. For those who don’t do too much diamond shopping (understandable, we look at a diamond and somehow all our meager savings are vacuumed out of our bank accounts) and are wondering why the prices for carats varies so widely, it’s because for the end consumer carats don’t really matter. It’s mostly about the cut that gives the diamond its value, rather than just its mass.

Second question for those wondering why the cut matters. The long short is that the cut can make a diamond look shinier and look like it has a higher carat weight.

Why are they called carats?

If you’re wondering where we got “carat,” well you’re probably not alone. But ever since people have been carrying around gemstones, people have broadly concluded that bigger and heavier is better. But what standard were people going to use?

Historically, people have used carob seeds. The carob is native to the Mediterranean and Middle East, and it was believed that their seeds carried little variance in weight. Carob seeds also allegedly weighed about as much as the smallest gemstone. The word “carat” is derived from “carob,” after going from Greek to Arabic to Italian–and then finally English (in that order).

The Karat

So onto the karat. Like we alluded to earlier, it doesn’t measure mass. The karat actually measures the fineness of a precious metal. There is some measurement of mass/weight involved, though. Also, we do know there’s a difference between mass and weight, but it doesn’t really matter for right now.

Now, fineness. The fineness of a precious metal is determined by how much of it there is in any given alloy. By definition, an alloy is a mix of chemical elements in which at least one is a metal. So for precious metal fineness, it’s about how much of the base precious metal there is–the proportion of which is determined by weight. So if you have a hunk of just silver, it’s at maximum fineness. If you’re working with silver you might have sterling silver, which is 92.5% silver by mass.

Further Reading: What’s the Difference Between Silver and Sterling Silver?

Karats are used exclusively for the measure of gold purity. Karats are also always done in terms of fineness per 24 parts whole, which basically means “what fraction out of 24 is my gold alloy actually gold?” That means 24 karat gold would be 100% gold, as 24 out of 24 parts of the alloy are gold. Truly 100% gold is basically impossible to get outside of a lab, so 99.95% gold qualifies for 24 karat when you’re buying stuff.

Here’s an unfun fact. You can still use “carat” when talking about gold. You can’t use “karat” to talk about precious stones like diamonds and gems, but you can use “carat” to talk about the fineness of gold.

Thank you, English.

If gold hasn’t gotten too gaudy for you yet, why not look at some gold stuff here?