Diamond Quality: the 4 C's

Shopping for a diamond can seem very daunting - especially if it's the first time. The first thing you want to do is familiarize yourself a little bit with exactly what aspects of a diamond determine its quality, and therefore its value. The GIA (Gemological Institute of America) created “the 4 C’s” in the 1940s to help us do just that. These universal and objective standards grade each individual diamond by Carats, Color, Clarity and Cut.  What’s more, it’s the combination of all these key four factors that determines the value of the diamond, not one single factor. For example, a diamond may be very large, but if it’s slightly flawed and not particularly clear, it may not be as valuable as you would first think.

Carats

A common misconception is that the term carats refers to the size of a diamond. Carats actually refers to the weight of the diamond. Of the four Cs, carat is the longest running standard in the industry and has been consistently used to appraise diamonds since the 1500s. The word itself originates from the carob seed, which was used as the counterweight to weigh gems on a scale.    

Diamonds are actually very lightweight: 6 carats is the equivalent of 1 gram. The carat measurement system also is highly precise - each carat can be subdivided into 100 points. For example, 0.05 carats can also be referred to as a 5 point diamond. There are some carat weights that are especially coveted, specifically quarter, half or full carats.

Carat weight in relation to diamond size. Image courtesy of Gemological Institute of America.

Color 

Color actually refers to the diamond’s lack of color. The less color, the higher the grade of the diamond. The GIA established an objective color scale in 1953 to create the objective standard for determining diamond color. The scale runs from D to Z, with D signifying the clearest color. There are strict standards for how the color of a diamond should be evaluated, from the specific lighting and background type to exactly how the diamond should be viewed. Color differences (especially between D-H) are very subtle as to be nearly invisible to the human eye - however, they make a big difference in diamond value and price.

Diamond Color. Image courtesy of Gemological Institute of America.

Clarity

The clarity of a diamond refers to how clear the diamond appears and is an assessment of small blemishes and inclusions. The GIA has also produced a Clarity Scale to substantiate a universal standard for diamonds, that is scientifically determined using a GIA patented microscope. This scale consists of six different categories and has 11 specific grades. The highest standard for diamond clarity is F, which stands for Flawless. This F grade means that the diamond has no inclusions or blemishes visible under 10x magnification. On the other end of the spectrum, I3 signifies that blemishes are Included - in other words, that the diamond has obvious inclusions that will affect the transparency and brilliance of the diamond.

Anything from VS2 and above usually does not show any inclusions or blemishes from a naked eye. 

Diamond clarity. Images courtesy of Gemological Institute of America.

Cut

Lastly, the cut, as the name would suggest, refers to the way the diamond is cut. The cut has a big impact on the diamond’s sparkle and the way it unleashes light - and that’s what makes it important. It’s also significant to note that it is not the same thing as diamond shape (e.g. round, cushion, pear, etc).

The cut of a diamond can be very subjective, which is why it can be a controversial aspect of diamond evaluation. The GIA uses the brilliant cut as its standard for grading diamonds - hence they have precise requirements and proportions for determining the quality of a brilliant cut. However, if you choose a diamond with an alternative cut, such as the rose cut or an old mine cut, this brilliant-cut standard isn’t applicable.  

Whilst the brilliant cut emphasizes the sparkle of a diamond as the light is unleashed outwards, the rose-cut offers the ability to look inside of the diamond and instead produces a glow, rather than glitter, from the light.

The key is to assess each rough diamond and then cut it in the best way to optimize its beauty and light.

The Brilliant Cut standard. Image courtesy of Gemological Institute of America.

The GIA's Cut Scale. Image courtesy of Gemological Institute of America.

Does anything else affect the quality and value of a diamond?

Although the 4Cs remain the current universal standard in the diamond industry and are certainly the most well-known elements in diamond lexicon, there are two other aspects of diamond valuation that you should be aware of.

Firstly, it's worth considering the fluorescence of a diamond. This refers to the level of visible light that a diamond emits when exposed to ultraviolet rays. Usually, this light has a blue hue, but can also sometimes look yellow or orange. In general, for higher quality diamonds with a color grade of H or above, blue-tinted fluorescence is considered less attractive. However, a GIA screening found that the fluorescence of a diamond only had a negligible effect on the appearance of diamonds.

The second aspect of diamond value that is often overlooked is the origin of the diamond. Like the terroir of a wine, where a diamond comes from had a deep impact on its features. A diamond from a South African mine will have a completely different feel to a diamond from Lesotho or even a diamond made in a laboratory. This is far more of a subjective feature to assess and evaluate in a diamond, but arguably equally as important as the Four Cs.

Nevertheless, the Four Cs offer a vital starting point to understand what makes a specific diamond special. Once you understand the 4C’s you can then start making decisions on what is most important to you. Is it the size? The clarity? The color? The cut?

In the end, every diamond and every ring is totally unique. All diamonds can be beautiful and there is the perfect diamond for each individual.

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