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Karat vs. Carat: What’s the Difference?

Catherine Tramell
Catherine Tramell

Published October 13, 2022

Last updated October 28, 2022

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If you’re out there looking to buy a precious metal or stone, you must know beforehand a few key aspects about them. You cannot just go out there and try to wing it, for the seller could take advantage of your naiveness.

If you know gold, you would have heard of the term “karat.” But do you know what karat means? And have you come across the word “carat?” Have you used the term interchangeably with “karat.” If yes, then that’s incorrect. Through this write-up, we’ll tell you why and more.

karat vs carat whats the difference

In this article, we’ll discuss:

  • What are karats and carats
  • How the two are different from each other and similar
  • What do the homophones carrots and carets have to do with karats or carats and more

In most ways, karats and carats are different. But in specific other ways, they may overlap. Read on to find out how and other essential aspects of the units of measurement.

What is a Karat?

The word “karat” denotes the amount of gold in a piece of gold. The 1/24th measurement scale that helps determine karat levels can be traced back to the times of ancient Rome when a “siliqua” (a silver coin) was considered the equivalent of the 1/24th part of a “solidus” (a gold coin).

The karat barometer begins at one and tops out at 24. A single karat indicates that 1/24th portion of a gold alloy is pure gold. If the gold item is the purest form of gold, it’s a 24-karat piece—i.e., all 24 parts of the article are fine yellow gold. If the fine jewelry is 22 karats, 22 of the 24 parts are pure gold; or 91.67% is yellow gold, and the remainder is other metals (copper, silver, nickel, etc.).

The lesser the karat number, the sturdier the gold since gold in its purest state is malleable or soft. Gold rings are usually 18 karats or less, so they don’t bend or lose shape with everyday use. To learn more about gold purity and the karat system, click here.

Read more: Types of Gold

Fewer karats not just mean lesser gold but also different colors. Standard gold colors based on the infusion of other metals include pink/rose gold and white gold. Other not very common colors include blue, green, brown, black, etc. You can make gold take up any color.

What is a Carat?

what is carat

“Carat” measures a gemstone’s weight (not size). Carat helps measure the gemstone mass of a diamond, ruby, sapphire, emerald, turquoise, opal, etc. Carat is one of the four Cs (carat, cut, color, and clarity) used as parameters to assess a diamond’s quality. It is arguably the most important of the Cs, greatly influencing the other three Cs.

A carat’s weight is 0.2 grams or 200 milligrams. A two-carat diamond is, therefore, 0.4 g or 400 mg in weight. A 10-carat diamond weighs two grams. If you know how much a diamond weighs but not its carats, divide the total weight (in grams) by 0.2 grams.

The weight of a diamond weighing less than a carat is denoted with carat weight points, such as 0.929 carats or 92 points. The 0.929 number could be rounded as 93 points. Carat numbers less than a single carat could be expressed as points, the exact decimals, or as three-quarter carat, half a carat, third carat, or quarter carat.

Carat Denotes Weight

Carat only specifies a diamond’s weight, not the gemstone’s size. Carat weight does not directly correlate with the size of the stone. In other words, the same carat weight diamonds can be of different sizes. A one-carat round-shaped diamond can be between 6.1mm to 6.8mm across, with the median being 6.5mm.

Why the size difference? Because some diamonds could be cut shallower or deeper. A shallow-cut diamond assumes a larger size to meet the weight requirements. Some diamonds may also have a thicker girdle or the outer edge where the gemstone’s bottom (pavilion) meets the top (crown).

The diamond shape could also dictate the size. The Asscher or square cut design, for instance, would measure smaller diagonally compared to a round cut diamond of the same weight. An oval-shaped diamond would be slightly bigger than the two.

Do bigger diamonds cost more? Yes, they do. Despite weighing the same, a more significant size diamond would cost more than a reasonably compact diamond since larger diamonds tend to be rare. In other words, the prices of diamonds are not purely based on carat numbers. If a 2-carat diamond costs $4,000, a 4-carat diamond usually costs more than $8,000.

Similarly, carats and diamond sizes do not necessarily correspond. If a two-carat diamond measures 10.5mm across, it’s not unusual for a 4-carat diamond to measure 12.5mm diagonally and not be double the size. Therefore, do not use carat as the only parameter when shopping for a specific diamond size.

The “Carob” Connection

Carob is a shrub/tree grown for its eatable pods. Native to the Middle East and the Mediterranean region, the carob tree is used in landscapes and gardens for ornamentation.

Several hundred years ago, there was no diamond carat or standard unit of measurement to weigh gemstones. The carob tree or carob beans were the only gemstone standards since they weighed almost identical to the smallest of precious rocks. Carob seeds became the base unit of measurement for weight.

Carat Etymology

The name “carat” has its origins in the Greek term “keration,” meaning the “carob bean.” It was then derived into Arabic as “qirat,” which means “bean pod” or “weight of four grains.” Qirat in Italian is “carato.” “Carato” is the closest inspiration for the term “carat.” Another school of thought, however, indicates “carat” is a play on “carratus,” a medieval Latin term used by alchemists back then.

And if you thought carats and carrots have some connection, there’s no relationship, except for the homophonic similarity. Similar is the linkup with “caret.”

“Caret” is the wedge-shaped sign (^) used by proofreaders and copy editors to denote the spot where a particular text must go. Although sounding similar to “carat” and “karat” and with a spelling almost identical to “carat,” it’s nowhere related to gold, diamonds, carrots, or anything expensive or edible.

People easily mix up “caret” with “carat.” Don’t be that person.

Karat and Carat: The Confluence and Incorrect Usages

Carat and karat are not just spelled differently. They are a lot more distinct than that. The following are how karat and carat coincide and differ:

Usage of the Terms

Contrary to general perception, referring to gold’s fineness or purity in carats is not incorrect. But it’s not standard practice.

The term “karat” came after “carat,” and it’s believed it got its inspiration from the latter. In some countries outside of the U.S., “karat” is spelled as “carat.” But it’s never the other way around.

The sentence, “Some of the gold buckles have 0.20 karat diamonds embedded in the center,” uses the wrong terminology. However, in this sentence, “He purchased a 14-carat gold Patek wristwatch retailing for above $15,000,” the usage of “carat” is acceptable.

The term “carat” has been used interchangeably with “karat” for centuries, starting around the 16th century. It’s, therefore, not surprising to see the practice continuing. Also, “karat” is typically used in its abbreviated form, “K,” in sentences. The term “carat,” however, is written in full primarily. You could sometimes use the abbreviations “ct.” or “cts.”


A 3-carat diamond may be more prominent than a 2-carat stone, but the two could look the same in color.

A 24-karat gold piece, on the other hand, would appear noticeably different than a 14 or even an 18K gold piece. The latter would be a slightly paler yellow, based on the other metals added. Even a 14-karat and 18-karat piece could have discernible color differences.

Diamonds could assume different hues, too, based on their color grades. Diamonds have 23 color grades categorized into four:

  • D-F (colorless)
  • G-J (near colorless)
  • K-M (faint)
  • N-R (very light).

Each letter grade has a distinct color appearance and price. Irrespective of their carats, diamonds can be made to assume a wide range of colors, such as green, pink, yellow, blue, etc.


Unlike a karat, a carat doesn’t alone determine the price of a diamond. Gold prices, on the other hand, are purely based on their karat rating, except for if the piece is truly unique or historically significant. A single-carat diamond could cost anywhere between $2,000 and $10,000 or sell for an even higher price. The other three Cs mentioned above play a significant role in pricing, particularly the “cut.”

Read more:A Comparison Between Brass and Gold


The terms “karat” and “carat” not just denote the specificities of two completely different expensive items, but their meanings are different too. Karat indicates the fineness of gold, whereas carat measures the weight of a diamond and other precious stones.

A one-carat and less-than-one-carat diamond could be the same size, but the prices may vary significantly. Besides carats, the quality of the cut, color, and clarity ascertain diamond prices. The better the cut, the more sparkly the diamond would be. It will also seem more significant.

Long story short, the value of gold jewelry is directly proportional to its karat numbers. With diamonds, on the other hand, carats are just one of the denominators. There are other things to consider that could influence the prices of diamond jewelry. While out shopping for either, knowing what the two terms mean will save you time, money, and hassle.


How big can a diamond be?

The largest diamond to have been dug is the Cullinan Diamond, comprising 3,106 carats. However, the standard or typical diamond size is nowhere near that. Your average diamond is usually between one and 1.2 carats. A one-carat diamond on an engagement ring is typically just above 0.5 cm in diameter.