The 4Cs of Diamonds:
Cut, Color, Clarity & Carat Weight

The most important characteristics to understand when making a diamond purchase are commonly known as a diamond’s 4Cs. When looking at a diamond, the components of cut, color, clarity, and carat weight all interact to give the diamond its unique beauty and durable structure.

All over the world, the diamond 4Cs have become a universally accepted method for assessing the quality of a diamond. But what do these components tell you about the best way to approach buying a diamond?

Well, no single diamond is ever perfect for everyone. Finding the right balance between the 4Cs for you will reveal your perfect diamond and lead to making a good investment. In order to help you do that, we’ve gathered our best advice and recommendations for how to consider each of the diamond 4Cs and how they work together.

The brilliance of a diamond is something truly incredible. The diamond’s ability to intensely transmit light and sparkle comes from how well a diamond’s facets interact with light. And that interaction comes from the cut.

Skilled craftsmen scrutinize each diamond to determine the best cut for a stone that will maximize brilliance through a balance of proportion, symmetry, and polish. Of all the 4Cs, the cut has the greatest effect on a diamond’s beauty and it is one of the first things you visually notice about a diamond besides its size.

While it may seem like a given that diamond cutters would cut a diamond for the most brilliance, fire, and scintillation, other factors are also considered. Depending on the cutter, they may decide to cut to retain as much carat weight as possible. This will leave a diamond too deep or too shallow for optimal light reflection. In another case, the diamond may be cut to minimize the appearance and number of inclusions. This will enhance clarity but diminish sparkle.

The GIA grades diamond cut on a scale of Excellent, Very Good, Good, Fair, and Poor. It is the most complex of the 4Cs to analyze because it is a subjective quality by nature and takes into account many other features of the diamond to conclude an overall grading. Note that only round diamonds get a Cut rating, because the theories behind light refraction cannot reliably predict light return of fancy shape diamonds (ie. oval, pear, marquise, emerald, radiant, etc) since every stone has a different length and width proportion.  

The important thing to remember about this most important component is that cut grading is not absolute. Many of our clients assume that an Excellent cut automatically means it is more brilliant and sparkly than a Very Good cut. The truth is that brilliance is complicated; our eyes not only see light returned, but color, contrast, and sharpness as well.

In showing three diamonds to five people, three to four different answers come back as to which diamond is the prettiest. The idea of cut rating is based on a formula, and this formula is frequently updated based on the latest research. Even the GIA and AGS, both highly respected labs, use a slightly different standard. That means there are some combinations of proportions that receive an Excellent cut at one lab, and Very Good cut at the other.

So the cut grading is a great way to filter out poorly-cut stones. But the best way to choose a diamond is still to see and to compare a narrow list of finalists in person.  

Hearing the term color can be a bit confusing when concerning diamonds, because the color grade is actually measuring the absence of color in a diamond. The GIA grades diamond color in terms of how white or colorless a diamond is on a scale from D to Z. The color grading of D is the highest grade and considered completely colorless. Finding natural diamonds with this grade is extremely rare. The color grading of Z indicates a diamond with noticeable yellow or brown tint.

Many of the color distinctions are far too subtle for the naked or untrained eye to detect. In fact, most professionals will need to observe diamonds side by side to detect which has the better and lesser grade. So when worn alone and enhanced by the metal used for the setting, the color of a diamond becomes a very workable feature.

Diamond pricing will be heavily impacted by the color grading though. There can be significant jumps in per carat cost of a diamond when moving up and down the color grading scale. It’s also important to note that a higher color grade is not necessarily advantageous if the cut detracts from the brilliance and sparkle of that particular stone.

For the color grade particularly, envisioning the finished product with the setting is a very helpful process to make sure you’re choosing something right for you. If you’re opting for a white gold or platinum setting, the more colorless grades will pair well and enhance the lack of color. If a yellow or rose gold setting is your preference, you may find that a diamond with a slight warmth in its color is a nice complement to the warmth of a colored metal.

Considering a diamond’s clarity is often painted as one of the more important of the 4Cs to consider. After all, this is the assessment of the imperfections on the surface and inside the stone. But many can get wrapped up in the size and location of the imperfections, when the actual meaningful consideration is whether the diamond is eye-clean.

When considering these characteristics, surface flaws are called blemishes and internal flaws are called inclusions. But even the GIA has taken to using the term “internal characteristics” instead of flaws. That phrasing better reflects the character and properties of a natural diamond and the inevitability of natural inclusions and blemishes.

Diamonds are formed through a natural process deep in the earth that involves incredible heat and pressure. As a result, less than 0.5% percent of all investment grade diamonds carry a clarity grade of Flawless (FL) and these will command a hefty price due to that rarity. Even Internally Flawless (IF) diamonds that can have small surface blemishes and inclusions only visible under 10x magnification are incredibly rare.

The vast majority of diamonds chosen by customers fall within the VVS (Very, Very Slightly Included), VS (Very Slight Included), and SI (Slightly Included) categories. Diamonds with these clarity grades will often appear as eye-clean with no visible imperfections to the naked eye.

The most important aspect of clarity for the look of your diamond is to ensure that inclusions are not interfering with light reflection. When this happens, the brilliance, sparkle, and overall beauty of the diamond appears dulled.

The term carat weight and size are often confused and used interchangeably. The carat number that accompanies a diamond refers to the weight, not its size. So when comparing diamonds with different carat weights, the cut can have a large impact. A high carat weight diamond with a Poor cut may look smaller than a diamond with a lesser carat weight and a Very Good cut.

The carat weight system started when early gem traders used a carob seed as a counterweight to balance scales. In the modern understanding, a “carat” is defined as 200 milligrams and each carat is divided into 100 points (to the hundredth decimal point). Most often you will see carat expressed with the abbreviation “ct” after the weight number.

Carat weight will have the most impact on diamond price of all the 4Cs since larger diamonds are more rare and desirable. However, that statement is dependent on the quality of the other 4Cs we’ve just discussed.

In the world of diamonds, there are also some common “magic sizes” that will save a jump in cost. For example, there’s very little difference between a 0.98ct diamond and a full 1ct diamond in weight or size, but the price difference can be substantial.