Karat vs. Carat: What's the Difference? (And Why You Need to Understand it Before Going Jewelry Shopping)

Shopping for jewelry can feel overwhelming—with endless options and prices that can be surprising.

On top of that, the complex terminology can make the experience feel like trying to read a sign in a foreign language. The jewelry industry certainly has very specific terminology, which can be difficult to understand without a bit of research.

Whether you’re shopping for a necklace, bracelet, ring, or earrings, you’ll encounter countless options—ranging from design styles and gemstone choices to setting types, chain styles, and more. With so many details to consider, it’s easy to feel overwhelmed. Fortunately, much of the jewelry terminology is readily available online, and any reputable jeweler will gladly guide you through the buying process.

In this article, we’ll focus on two of what may be the most confusing jewelry terms of all: carat and karat. You’re not alone if you have confused these two terms, as even experienced jewelry shoppers can get tripped up with these. Although they sound the same, they mean very different things. Karat applies to metal and carat applies to gemstones. One measures purity and one measures weight. Understanding the difference between these two terms will make jewelry shopping much easier and help you make more informed purchases. 

What is a karat?

Karat (spelled with a “K”) refers to the purity of gold metal. When you see a piece of jewelry with a metal stamp labeled 22K, 18K or 14K, it refers to the karat of the metal. Gold purity is measured in karats with the highest karat being 24K (pure gold). Although 24K is the brightest yellow version of gold, it is too soft to be used in jewelry, since jewelry will be worn and must last the test of time. 

Understanding karat values and gold colors

Pure gold is very fragile and can be easily damaged. Therefore, 24 karat gold is often mixed with other metals to create an alloy. This is how gold is used in most modern jewelry.

• 24K: 100% pure gold. In this state, the metal is a very bright yellow and very soft.
• 18K: 75% gold and 25% other metals. 18K gold is often used in fine jewelry, but is still a bit soft to be worn on a daily basis. It is a rich yellow color.
• 14K: 58.3% gold and 41.7% other metals. 14K is the most popular choice for fine jewelry, including engagement rings and wedding bands. It still has a beautiful color, but is also durable enough to withstand daily wear and strong enough to hold precious gemstones.
• 10K: 41.7% gold and 58.3% other metals. 10K is the minimum gold content to legally be called gold in the United States. It is a harder metal, but is not often used in fine jewelry. It has a much more muted color tone than higher karat metals.

Each metal karat has pros and cons. 24K might be the most vibrant yellow, but it is not sturdy enough for durable jewelry. 14K and 18K gold are widely used in jewelry because the alloy makes them strong enough to be worn daily, but the color is not as vibrant. Certain alloys may cause skin allergies, so it’s best to research this before making any jewelry purchase. The metals added to create alloys can affect the color of the metal, which is why 24K gold has a deep, rich yellow color, while 14K yellow gold will appear a lighter yellow. The addition of copper to pure gold creates the pink tone in rose gold, and the combination of pure gold with nickel or palladium creates white gold. 

What is a carat?

Now it’s time to discuss carat, spelled with a “C”. Carat refers to gemstone weight and is most often used for diamonds. One carat is equal to 200 milligrams, or 0.2 grams. Carat weight is one of "the 4Cs" and is very important in diamond and gemstone grading, as it has a significant effect on the value of the stone. 

Does carat refer to the size of a diamond?

While some may think that a carat refers to the size of the gemstone, it does not, as gemstone size is measured in millimeters. Instead, carat specifically refers to the weight of the stone. This is important since each stone is unique. For example, you might come across two stones that both measure 6.5mm in diameter, but one could weigh 1.01 carats while the other weighs 1.05 carats. This difference of 0.04 carats is a huge difference in the jewelry world.

This may seem slightly confusing, but keep in mind that weight depends upon the proportions of the stone–sometimes referred to as cut.

How do you measure carat weight?

Carat weight is measured in points, so one carat equals 100 points, often written as 1.00ct. If you are looking at a gemstone that weighs 0.75ct., you could say that it weighs 75 points as well. However, note that when discussing stones larger than 1.00 carat, you wouldn’t really use the point system. 

How karat and carat affect jewelry pricing?

Both karat and carat influence jewelry pricing, but in different ways. The higher the karat, the more expensive the jewelry tends to be, simply because 24K has a higher percentage of pure gold. The same goes for carat where the larger the carat, the more expensive the stone (in most cases), but this also depends upon the other three of the 4Cs, which are color, cut, and clarity. You can learn more about the 4Cs here.

How to save money on a 1 carat diamond?

There is a helpful trick to remember when shopping for diamonds that can save you a little money, though! The average person searching for an engagement ring typically has a goal of a 1.00 carat center stone, but the truth is that if you purchase a stone just under 1.00 carat, the price will be more economical. If your goal is to have a total weight of 1.00 carat, we recommend purchasing a slightly smaller stone and using the savings to add accent diamonds, which will bring you over the 1.00 carat total weight.

Hopefully this quick lesson has given you a better understanding of the difference between karat vs. carat. Jewelry shopping doesn’t have to be as overwhelming as learning a foreign language. Regardless of which type of jewelry you're looking for, understanding the difference between karat and carat will make you feel more empowered to make an educated purchase.