Choosing the Perfect Diamond: The Four Cs

Check out our quick guide to determining which diamond is the right one for you (or your significant other)!
The 4C's of diamond grading
farah prince the knot fashion and beauty expert
by Farah Prince
farah prince the knot fashion and beauty expert
Farah Prince
Fashion and Beauty Expert
  • Farah Prince is a Digital Merchandising and Content Senior Analyst at Luxottica.
  • Farah is a fashion and beauty e-commerce merchandiser with experience driving retailer sales.
  • Farah worked as a Fashion and Beauty Assistant for The Knot from 2017 to 2019.
Updated Jul 17, 2018

When you begin researching the perfect engagement ring for your significant other, the word "overwhelming" may come to mind. Before you even make the purchase, a number of factors, from budget to style, have to be considered. And while a lot of the old rules no longer apply when choosing an engagement ring, like having to buy one that is "traditional," there are some guidelines you should always keep in mind when shopping for a diamond ring. If you're thinking of a buying a white diamond, the 4Cs—cut, color, clarity and carat—are important to consider before settling on a ring. Editor's note: No standardized quality grading system exists for colored gemstones, so if you're on the hunt for a colorful center stone, these rules don't apply. 
Special thanks to Adelaide Polk-Bauman, Forevermark Diamond Expert, and Benjamin Javaheri, founder of Uneek Jewelry, for their expertise.


4Cs of Diamond Grading - Cut

The cut of a diamond isn't actually the size or shape of the diamond, but rather the angles and proportions of the stone. It is the only one of the four Cs that's not determined by nature and is the most important quality to consider. If the diamond is cut too deep or too shallow, it will leak light on the sides, giving it a lackluster appearance, which will reduce its value and brilliance. A well-cut diamond will have two factors: mirror-like facets and a "white light" reflected both internally and externally, also known as the brilliance, or what will make your engagement ring shine bright.


4Cs of Diamond Grading - Color

A structurally perfect white diamond has no hue. The degree of a diamond's colorlessness is graded on a scale from D (colorless) to Z (light yellow), with colorless stones being the most valuable.

As a general rule of thumb, a colorless diamond will cost your more than a colored stone, unless the color is extremely rare (think: green or red diamonds).


4Cs of Diamond Grading - Clarity

The less impurities or inclusions a diamond has, the clearer and more expensive it is. Inclusions occur when the diamond forms in the earth's mantle, as it was crystallized under heat and pressure, so while there are treatments that boast creating a clearer stone, a "flawless" diamond is extremely rare. Similar to color, the clarity of a diamond is also measured on a scale. Diamonds that are graded in the SI1 and SI2 range are slightly included but their imperfections are often invisible to the naked eye.


4Cs of Diamond Grading - Carat

Carats refer to the weight of the diamond. As the carat size increases, so does its rarity and, of course, its price tag. But a diamond that has a bigger carat weight doesn't necessarily mean it will look bigger. A diamond with a smaller carat size but a shallow cut may look larger than a diamond with a bigger carat size and a deeper cut. The appearance of size all depends on not only the shape of the diamond, but the different designs and mountings you choose—a halo will make a smaller stone appear larger, and so will a shape with more surface area, like a pear or emerald.

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