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The Four Cs of Diamonds

by David Weliver

The 4 Cs of diamonds are the primary criteria independent gemological laboratories use to grade diamonds. A diamond’s grade determine its value and price.

Learning the four Cs is an essential step as you prepare to buy a diamond. Because every diamond is unique, the four Cs provide an objective standard by which you can compare two or more stones.

What are the four Cs of diamonds?

The four Cs of diamonds refer to the diamond’s cut, color, clarity, and carat (weight or size).

Cut

A diamond’s cut is arguably the most important of the 4 Cs because it has the biggest impact on the stone’s brilliance (or how much it sparkles).

Although the word “cut” is sometimes used to describe a diamond’s shape — as in, a princess-cut diamond — a diamond’s shape is not one of the four Cs. Rather, cut refers to the diamond’s cut quality.

How well a diamond cutter does their job affects how light is reflected through the gem and, as a result, how beautiful and fiery it appears to the human eye. Cut is arguably the most important of the four Cs.

More: Learn more about diamond cut quality

Color

Most people think of diamonds as white or clear, but in reality they come in a wide range of colors, from transparent or “colorless” to yellow or brown.

When it comes to white diamonds, the less color a diamond has, the higher the grade and, consequently, the value.

White diamonds are graded on a letter scale, with D, E, and F being the highest “colorless” grades. The closer to Z you get, the more of a yellow tint the diamond will have.

Some other colored diamonds (blue for example) are unique and therefore may be extremely valuable, although these are graded differently.

More: Learn more about diamond color

Clarity

Clarity refers to how clear or “clean” a diamond is.

Diamonds are a natural substance and, as a result, most of them are not perfect. They come out of the ground with imperfections. In the gem world these are called inclusions.

Diamond graders use magnifiers to spot these inclusions and determine how they impact the gem’s appearance. This grade is called diamond clarity.

The fewer inclusions a diamond has, the more valuable it will be. It’s worth noting, however, that many inclusions are not visible to the naked eye.

More: Learn more about the diamond clarity grade

Carat

A carat is a unit of mass (weight) used to measure diamonds and other gems. It should not be confused with the homophone karat, which is a unit of a precious metal’s fineness (as in 14-karat gold).

The higher a diamond’s carat-weight, the larger the stone.

Fun fact: The Cullinan Diamond is the largest gem-quality rough diamond ever found. It weighed 3,106 carats (621 grams) when it was mined. The diamond was cut into many gems, but the largest is known as the “Cullinan I” or the “Great Star of Africa”. It weighed 530 carats and is the largest clear cut diamond in the world. The diamond is currently one of the Queen of England’s crown jewels and is valued around £41 million ($54 million).

For comparison, most people buy engagement rings with diamonds sized between less than half of a carat to about two carats.

More: Learn more about diamond carat weight

Beyond the 4 Cs

The 4 Cs are the most important characteristics that determine a diamond’s rareness and value. That said, other factors including a diamond’s shape and origin can also affect its value.

Learn more about how to shop for and compared diamonds in our diamond buying guide.

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