Understanding Diamonds: A Practical Guide to the 4 C's

Diamonds are far more than just a symbol of luxury – their beauty is the marriage between the magic of nature and the craftsmanship of man. 

For those who are looking to understand these stones, becoming familiar with their descriptions and metrics can seem daunting.  The 4 C’s—Colour, Clarity, Cut, and Carat Weight—provides a framework for understanding diamonds, and what makes each stone unique. 

In this article, we will identify each of the 4Cs and give an explanation of each. Our goal is to help inform you so that you will be well equipped to make a sound decision when choosing the perfect diamond for your next piece.

Colour

A diamond’s colour—or rather, the absence of it—plays a pivotal role in determining its value and appeal.

The Gemological Institute of America (GIA) uses a standardised colour scale used to gauge the color of a diamond. It begins with ‘D’, and extends to ‘Z’.

GIA Colour Scale
Fig 1. The image displays the Gemological Institute of America (GIA) Diamond Color Scale, which ranges from D (colorless) to Z (light yellow). It illustrates the progression of color in diamonds from completely colorless to those with a yellow hue

The ‘D’ grade represents a completely colourless diamond, which is extremely rare and, as a result, highly valued. As we move down the scale, each letter signifies a gradual increase in the presence of colour, typically yellow or brown hues. These tints, albeit subtle, are significant indicators of the diamond’s chemical composition and the environmental conditions it was exposed to deep within the Earth. For instance, the presence of nitrogen can give diamonds a yellowish tint.

This scale is meticulously nuanced with each grade representing a slight variation in colour. The differences between one grade and another are often so subtle that they require expert eyes and controlled lighting conditions for accurate assessment.

Colour grades from ‘D’ to ‘F’ are considered colourless, ‘G’ to ‘J’ are near colourless, and ‘K’ to ‘Z’ show increasing levels of colour.

Clarity

Clarity is another critical factor that assesses the purity and perfection of a stone. Clarity is defined by the presence, or absence, of inclusions and blemishes—imperfections that can occur naturally within or on the surface of a diamond. These inclusions and blemishes are formed by a variety of factors such as crystal growth, trace minerals, and structural imperfections. 

The GIA has established a clarity grading scale that is widely recognized and used in the diamond industry. This scale classifies diamonds based on the visibility, number, size, and position of these inclusions and blemishes.

Fig 2. This illustration presents the GIA Clarity Scale for diamonds, ranging from FL (Flawless) with no inclusions or blemishes visible under 10x magnification, through to I3 (Included) where inclusions are obvious under 10x magnification
Fig 2. The image presents the GIA Clarity Scale for diamonds, ranging from FL (Flawless) with no inclusions or blemishes visible under 10x magnification, through to I3 (Included) where inclusions are obvious under 10x magnification
  • Flawless (FL): Diamonds graded as Flawless have no inclusions or blemishes visible under 10x magnification. They are exceptionally rare and represent the pinnacle of purity.
  • Internally Flawless (IF): These diamonds have no inclusions and only insignificant surface blemishes when observed under 10x magnification. They are nearly as rare as Flawless diamonds.
  • Very, Very Slightly Included (VVS1 and VVS2): Diamonds with these grades have inclusions that are so slight they are difficult for even a skilled grader to see under 10x magnification. The difference between VVS1 and VVS2 involves the location and visibility of these inclusions.
  • Very Slightly Included (VS1 and VS2): These diamonds have inclusions that are observed with effort under 10x magnification but are considered minor. The distinction between VS1 and VS2 typically involves the inclusions’ size, number, and location.
  • Slightly Included (SI1 and SI2): Inclusions in these diamonds are more easily observed under magnification and can sometimes be seen with the naked eye, especially in larger diamonds.
  • Included (I1, I2, and I3): Diamonds in these categories contain inclusions that are obvious under 10x magnification and may affect transparency and brilliance. These inclusions can often be seen with the naked eye.
The clarity of a diamond is a key determinant of its beauty since natural inclusions and blemishes can interfere with the path of light that shines through the stone. This interference can diminish the stone’s ability to refract light and produce its characteristic sparkle and fire. However, it’s important to note that many inclusions and blemishes are microscopic and do not significantly impact a diamond’s appearance to the unaided eye.
 
Clarity is often considered the most subjective C. Gauging it often depends on the individual grader’s subjective assessment. 
 

Cut

The cut of a diamond is a critical factor that significantly influences its interaction with light, dictating its brilliance, fire, and scintillation. 

Unlike the diamond’s colour and clarity, which are determined by nature, the cut is the result of human craftsmanship.

It encompasses the diamond’s shape, the quality of its proportions, symmetry, and polish. Each shape has ideal proportions and angles designed to maximize light performance, and the craftsmanship quality reflects the precision in achieving these ideals.

The GIA has a grading system for judging a diamond’s cut. The grades are as follows: Excellent, Very Good, Good, Fair, and Poor. This grading system depends on both the optical properties of the diamonds and also its physical components. To put it simply – a diamond with an excellent cut exhibits a high degree of brilliance and scintillation – it looks great. And a diamond with a poor cut looks dull and lifeless. 

Fig 3. The image illustrates the GIA Cut Scale for diamonds, which evaluates the quality of a diamond's cut and its effect on the stone's brilliance and fire.

In the realm of diamond evaluation, the cut is often the C that is considered the most important among the others —since it has a significant impact on a diamond’s interaction with light and therefore its brilliance and beauty. A well-crafted cut enhances a diamond’s brightness, colour dispersion, and sparkle, while a poorly executed cut can diminish these attributes, making even a diamond of high colour and clarity appear lacklustre.

This is what makes the beauty of a diamond unique. Its aesthetic appeal is the result of the combination of nature and the craftsmanship of man.

Carat Weight

“Carat Weight” is one of the most recognizable terms when it comes to diamonds. The term originates from the historical use of carob seeds as a standard for weighing due to their uniform size. One carat equals to 0.2 grams, serving as a measure of a diamond’s weight. Larger diamonds are rarer and, consequently, more valuable because large natural crystals are scarce. 

Relative Diamond Carats
Fig 4. Round cut diamonds of varying carat weights and their respective diameters.

It’s important to note that a diamond’s value goes beyond carat weight. Even though a diamond’s carat is the most easily recognizable metric, its overall appeal and value are significantly influenced by the cut, colour, and clarity. The cut, in particular, plays a crucial role in a diamond’s perceived size and brilliance. 

Your Journey to the Perfect Diamond

With a diamond’s cut, colour, clarity and carat, choosing the perfect stone for your next piece can seem like a daunting task. With so many different characteristics of these stones, the trick is finding a perfect balance that resonates with your personal sense of style, and your budget.

At Studio Jewellers, our team has over 40 years of experience in creating custom diamond pieces from scratch. We have a deep understanding of diamonds, and can help you navigate their world so you can make an informed decision. Furthermore, with connections to diamond dealers across the globe, we can help you source the perfect stone for your next piece. We warmly invite you to get in touch with us or visit us at our local showroom in Calgary for a complimentary consultation