What is Carat Weight (ct), Carat Total Weight (ctw), and Karat?

by | Jun 8, 2023 | buying a diamond, Lab Grown Diamonds

Demystifying Carat Weight, Carat Total Weight, and Karats: The Key to Unlocking the Value of Your Jewelry


When it comes to jewelry, there are a few key terms that are essential to understand in order to make informed decisions about buying or selling. These terms include carat weight, carat total weight, and karat.

While they may sound similar, each term refers to a different aspect of jewelry and has its own significance in the industry. Understanding carat weight is particularly important when it comes to gemstones.

Carat weight is a measure of how much a gemstone weighs and is often used as an indicator of size. The higher the carat weight, the larger the gemstone will be.

Carats are also used as a measurement of purity for gold jewelry. The term karat refers specifically to the percentage of gold in an alloy, with 24k gold being pure gold and 10k gold containing only 41.7% gold.

Carat total weight refers to the combined weight of multiple gemstones within a piece of jewelry. This can have a significant impact on the overall value and price of the piece.

In this article, we will provide detailed explanations for each of these terms so that you can better understand their importance in the jewelry industry. We will also provide examples and practical advice for using these terms when buying or selling jewelry.

Key Takeaways
  • A well balanced harmony between all 4 factors determine a diamond’s grace and sparkle.
  • Carat Weight is the measurement of a diamond’s weight and can factor into the value of the stone.
  • Clarity refers to the amount of blemishes and flaws included in the stone itself – the less flaws, the higher the clarity and the value.
  • Color is graded by shades away from colorless – the less color a diamond has the more valuable it becomes.
  • Cut is the final C and determines how well light is reflected and refracted from the stone, giving it’s eye catching sparkle.

This engagement ring has a total weight of 4.65ctw; 3ct in the center stone, and 1.65ctw in the smaller side diamonds

The Importance of Carat Weight

Carat weight is one of the most important factors to consider when purchasing or valuing precious stones such as diamonds, rubies or sapphires. This measurement determines how much material was used in cutting and polishing these stones while working with artisans at every step from mining until their production as polished gems for sale on marketplaces. For example, two diamonds with identical clarity grades can be valued very differently if one is significantly larger than the other due to differences in their respective diamond carat weight.

It’s important to note that carat weight is not the same as size, as certain gemstones can be denser and therefore weigh more than others of the same size. For example, a one-carat diamond will typically be smaller in size than a one-carat emerald, although they have the same carat weight.

When considering diamond carat weight, it’s also important to keep in mind that larger stones are generally rarer and more valuable. However, this can also make them more expensive and difficult to find.

What is Karat?

Karat refers to the purity of gold in an alloy. Pure gold is too soft to use in jewelry making, so it is often combined with other metals like copper or silver to increase its durability and strength.

Karat measurements range from 24k (pure gold) down to 10k (41.7% gold). The karat measurement can affect the color and durability of the resulting alloy, as well as its value.

For example, 18k gold contains 75% pure gold and 25% other metals like copper or silver. This creates a stronger alloy that is less likely to tarnish over time compared to a lower-karat alloy.

It’s important to note that the karat measurement only refers specifically to the percentage of gold in an alloy – it does not necessarily indicate quality or value. A well-crafted piece of jewelry made from 10k gold could be just as valuable as a piece made from 18k gold if it has intricate designs or high-quality gemstones.

The Significance of Carat Total Weight

Carat total weight (ctw) refers specifically to the total weight of multiple gemstones within a piece of jewelry. This measurement can have a significant impact on the overall price and value of the piece. For example, when purchasing diamond stud earrings, it’s common for both earrings to have equal carats weights so that they appear symmetrical.

If one earring has a significantly higher carat weight than the other, this can detract from the overall value of the set. When purchasing a piece of jewelry with multiple gemstones, it’s important to calculate the ctw in order to accurately determine its value.

This can be done by weighing each individual stone and adding up their total weight. In some cases, ctw can also be used as a marketing tool – for example, a diamond tennis bracelet may be advertised as having a total carat weight of 5ctw to make it seem more valuable and impressive.


Understanding carat weight, karat, and carat total weight is essential when it comes to buying or selling jewelry. These terms have significant impact on the value and price of pieces and should not be overlooked.

By knowing these terms in detail you will be well equipped to make informed decisions about purchasing jewelry that is both beautiful and valuable. It’s worth taking the time to learn about these concepts so that you can get the most out of your investment in this timeless industry.

Carat Weight (ct)

Defining Carat Weight

Carat weight refers to the unit of measurement used to express the weight of a gemstone or diamond. One carat is equal to 0.2 grams, or 200 milligrams, making it a very small unit of measure. The term “carat” is derived from the Greek word keration, which translates to “fruit of the carob tree.” Ancient gem traders would use carob seeds, which were uniform in size and weight, as counterweights for their gems when measuring them. Carat weight does not at all reflect a diamond’s quality.

Measuring and Calculating Carat Weight

To determine the carat weight of a gemstone or diamond, it must be weighed on an extremely precise scale that can measure down to fractions of a carat. A digital scale is used in most cases for accuracy. The weight is typically rounded up or down to the nearest hundredth of a carat for simplicity and ease of communication in the jewelry industry.

The Impact on Value and Price

The higher the carat weight of a gemstone or diamond, the more expensive it will be because larger stones are more rare and desirable. For example, a one-carat diamond will generally cost significantly more than two half-carat diamonds even though they have the same total carat weight (ctw). When evaluating gemstones and diamonds for purchase or appraisal purposes, a diamond’s carat weight is one factor that contributes greatly to its value.

Examples of Popular Gemstones

Gemstones come in many different sizes and shapes but certain ones are commonly found with specific average weights. For example:

– Amethysts: 1-20 ct – Aquamarines: 1-15 ct

– Citrines: – 1.00 ct-20 ct – Emeralds: 0.05-10 ct

– Rubies: 0.05-10 ct – Sapphires: 0.05-15 ct

– Topaz: 1-20 ct It’s important to keep in mind that these are just average weights, and that gemstones of the same type can vary greatly in size and carat weight based on their individual characteristics.


Carat weight is an essential factor in determining the value and desirability of a gemstone or a diamond ring. Understanding how carat weight is measured, calculated, and its impact on price is crucial for anyone interested in buying or selling jewelry. Knowing the typical carat weights for popular gemstones can also be helpful when making purchasing decisions.

Total Carat Weight (ctw)

When buying a piece of jewelry with multiple gemstones, such as a diamond tennis bracelet or stud earrings, you will often see the abbreviation ctw. Carat Total Weight (ctw) is the combined weight of all the gemstones in a piece of jewelry. This includes diamonds, colored gemstones, and other precious stones.

Calculation of ctw

The calculation of ctw is relatively simple. You take the weight of each stone and add them up to determine the total weight. For example, if you have a pair of stud earrings with two diamonds that weigh 0.5 carats each, then the ctw would be 1 carat for both earrings combined.

If a piece has multiple stones that are not all identical in size or shape, then calculating ctw becomes more complex. In this case, you would need to weigh each stone individually to determine its carat weight and then add them up to get the total ctw for the piece.

Keep in mind that some retailers will include the center stone in their stated total diamond weight. It is important to know this so you know what you’re getting and paying for. For example, if an engagement ring has a center stone where the diamond weighs 1cts, and total diamond carats for the entire ring is stated as 1.5ctw on the description, you want to make sure you know whether or not the center diamond is included in that. Some jewelers set up cubic zirconia as the large center stone in display rings, even though all of the small diamonds are real, so this will not always include the weight of the center stone.

The significance of ctw

Ctw is an important factor in determining the value and price of a piece of jewelry because it takes into account all the stones involved in making it. The higher the total carat weight a piece has, generally speaking, the higher its value will be. It’s important to note that even if two pieces have the same total carat weight, they may still differ greatly in value due to other factors such as cut quality or diamond clarity.


Diamond tennis bracelets are one example where ctw is used extensively. These bracelets are made up entirely of diamonds set next to one another in a row and come in various sizes based on their total carat weight. For example, a 3ctw diamond tennis bracelet may have 50 diamonds each weighing 0.06 carats. So the combined individual carat weights of each diamond is included in that 3ctw.

Alternatively, it may have fewer diamonds with larger total carat weight such as a ring with 25 diamonds each weighing 0.12 carats. Stud earrings are another common piece of jewelry measured by ctw.

A pair of diamond stud earrings could have two diamonds each weighing 1 carat for a total carat weight of 2 carats. Keep in mind that the quality of the diamonds or other gemstones involved can greatly affect the value and price of a piece despite having the same total carat weight as another piece with lower or same quality of stones.

Carat Total Weight is an important factor to consider when purchasing jewelry with multiple gemstones, or a diamond ring with multiple diamonds. It is calculated by adding up the individual weights of all the stones in a piece and can be used to help determine its overall value and price. When shopping for jewelry based on ctw, it’s important to also consider other factors such as cut quality and gemstone clarity to ensure you get the best deal for your money.

A three stone ring is another great example of this. This type of ring will have one diamond in the center, typically larger diamonds, with two smaller diamonds on each side. If a ring is marked at 3ctw, of all the diamonds, for example, and the single stone diamond in the center is stated to be 2ctw, then the diamond’s weight left is 1ctw. Typically those two sides stones don’t have different carat weights, so each single diamond on the side will be 1/2ct each.

Karats (K)

Definition and Explanation of Karats

In the world of jewelry, karat (K) is a measure of gold purity. Pure gold is 24 karat, but it is too soft to use in jewelry.

Therefore, gold must be mixed with other metals to make it more durable. The percentage of pure gold in a piece of jewelry determines its karat rating.

How Karats are Used to Measure Gold Purity

The karat rating indicates the percentage of pure gold in a piece. For example, 18k gold has 75% pure gold and 25% alloyed metals. Jewelers often stamp the karat rating on pieces to indicate their purity level.

The Difference Between 24k, 18k, 14k, and 10k Gold

The most common karat ratings for gold used in jewelry are 24k, 18k, 14k, and 10k. 24-karat gold is the most pure form of gold used in jewelry but it is also too soft to be practical for everyday wear or even special occasions as it can get damaged easily. 18-karat (75% pure) has a warm yellow color that many people find pleasing due to its rich color compared to lower rated ones.

14-karat (58.5% pure) is one of the most popular choices since it’s harder than higher-rated ones because it contains more alloyed metals making it more durable yet still have high value 10-karat (41.7% pure) offers greater durability and affordability than higher rated ones for everyday wear but with less value due to lower purity.

How Karats Can Affect the Durability, Color, and Value of Gold Jewelry

The percentage of alloyed metals that are mixed with pure gold determines the durability, color, and value of gold jewelry. Higher karat ratings result in softer gold that is less durable but more valuable due to its higher percentage of pure gold. Lower karat ratings make for more durable jewelry pieces because it contains more alloyed metals but it has less value due to a lower percentage of pure gold and a less intense yellow color than higher-rated ones.


Understanding the karat rating is important when buying or selling gold jewelry. The percentage of pure gold affects both the durability and value of the piece.

The karat rating can also affect the color of the piece. Knowing about Karats will help you make an informed decision when purchasing your next piece of diamond jewelry.

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About the Author

Matt O'Desky

I grew up in Chicago where we always had a “Diamond District” – an area of town with a slew of buildings filled with dozens of private jewelry wholesalers and upstairs diamond dealers.

When I moved to Texas, and realized there were few if any private jewelers, and I knew what I should do: Deliver a far more personalized experience, in a far more relaxed and enjoyable environment than any department store jeweler could possibly offer.

And show my clients obviously better diamonds at clearly better prices.

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