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4Cs of Diamonds:
Diamond Carat

Diamond being measure on a black background

When it comes to fine jewelry, a diamond’s appeal and value are often dictated by a combination of the 4Cs – its cut, clarity, color, and carat. Although each of these Cs is incredibly important, carat is oftentimes the first and only C that comes to mind for prospective shoppers. In this article, we’ll go over what a carat is, and how it relates to a given diamond’s size, price, and beauty.

What is a Carat?

Often misunderstood, a diamond’s “carat” is not a measurement of its size. Rather, it’s a measurement of its weight. One carat is equal to 200 milligrams, or 0.20 grams. The term has its origins from ancient times when gem traders used to weigh stones against carob seeds to determine their approximate weight. Carob seeds are incredibly consistent across each other for weight, hence they were used as a scaling standard when no other accurate weighing tools were present.

Carob pods and carob beans on the wooden table.
Fig 1. Carob seeds, having consistent weights among themselves, were used by ancient gem traders as a standard for determining the approximate weight of gems.

Another term that you’ll hear along your diamond journey is total carat weight, or TCW. Total carat weight is a measure of the carats of all the diamonds of a given piece. So for instance, on a solitaire ring the TCW would take into account only the single stone, whereas on a pave ring, the TCW would take into account the multiple stones present.

Diamond Weight and Size

While a greater weight generally means a bigger size, this isn’t always the case. Since every diamond is cut differently, certain cuts lend themselves to having greater proportions allocated to certain areas of the diamond, altering its perceived size.

For instance, for diamonds that are cut deeply, a lot of their weight is allocated to its depth, causing a greater proportion of the diamond to be hidden from the front facing view. On the other hand, diamonds that are cut too shallow have a greater proportion of their weight allocated along their diameter, leading to a larger front facing facet.

Diamond cut chart guide
Fig 2. The cut of a diamond is important not only because it affects its light performance but also because it influences how the diamond's carat weight is distributed across its dimensions. Depending on the cut, the weight can be distributed in various ways, affecting perceptions of its size

In either case, diamonds that are cut too deep or too shallow lead to sub par light performance. This means that the classic look of the diamond’s brilliance that is often sought after is stunted. When shopping for a diamond, it’s important to pay special attention to its cut, as it’s the factor that has the biggest impact on a diamond’s aesthetic appeal.

The Significance of Carat in Diamond Value

Generally speaking, a diamond’s price increases with its carat weight, given that all other factors remain consistent. Note though, that this relationship isn’t completely linear. For example, a diamond of 2 carats is not twice as expensive as a diamond that’s 1 carat – it’s generally much more.

This is because it is much rarer to find the raw diamond that is needed to create a finished stone of a high carat than to find the raw diamond needed to create stones of lower carats. Hence, the price of higher carat diamonds can be considerably higher.

As much as a diamond’s value is influenced by carat weights, remember that it’s also influenced by its cut, color, and clarity as well. This means that there are diamonds on the market with the exact same weights, but with wildly different appearances and prices.


Understanding the carat is a crucial part of making an informed decision when purchasing your next loose diamond or diamond jewelry piece. As important as it is, though, it should be evaluated among the cut, color, and clarity as well. A smaller diamond with an excellent cut, color, and clarity will oftentimes look better than a larger stone with subpar quality. All things considered, each diamond is unique and finding the right stone is about finding what fits both your tastes and budget.

With over 40 years of experience in the industry, our team has worked with diamonds of all carats and sizes, ensuring a perfect match for every preference and occasion. We invite you down to our showroom in San Diego, where our GIA graduate gemologist can help guide you along your purchase journey. Schedule a consultation with us today and see why San Diego locals have been coming to us for their jewelry for over 40 years.