You may have heard of the 4 Cs when it comes to diamonds. It’s a basic guide on how to look at and grade diamonds. It’s also a great starting point to understanding what makes one diamond more valuable than another and how best to choose one for yourself. The 4 Cs stand for Colour, Carat, Clarity and Cut. They are used around the world to categorise diamonds and specially trained diamond graders will evaluate each single diamond for all 4 of them.
We’ll go into a little bit more detail about each here and how diamonds are evaluated for each category.
If you’re wondering, "how do I choose a diamond?", take a look at our tips below:
Colour
Typically, when we think of diamonds, we imagine them to be colourless. In fact, diamonds can come in all shades of the rainbow – red, violet, blue and pink are the rarest colours and most desirable, but they also come in gorgeous yellows, greens, oranges, and browns. These unusual colours of diamonds are called ‘fancy colours’ and are graded differently depending on the intensity of their colour. We’ll do another post on these beauties!
Most diamonds you will see day to day, however, are on the colourless scale. This grading scale starts from ‘D’ for completely colourless to Z for a highly tinted stone (usually yellow or brownish). As soon as a diamond has a properly discernible colour rather than just a tint, it is graded as a fancy coloured diamond instead.
A diamond is graded face down for colour in a special environment by diamond graders who a trained to see the subtle colour differences.
If you want a colourless or ‘white’ diamond, it’s best to stick to the top end of the alphabet (D, E, F). These colour grades are the rarest and generally the most desirable, thus they attract the highest prices. G colour diamonds, while very faintly tinted from the side, generally still look quite white from face up. From H to I colour, however, you may start to see a slight tint to your diamond from face up. All modern diamonds in Aril Jewels pieces are of F colour and above. Our antique old cut diamonds vary a little more, although we do our very best to select only the whitest diamonds, never going beyond H colour.
Image 1 - Colour scale examples, GIA website
Carat
Most people think carat refers to the size of a diamond, and this is partially true. A carat is a unit of measurement and determines how much a diamond weighs. It is equivalent to 0.2 of a gram. Generally, the larger the carat weight, the bigger the stone will appear. However, the cut (the fourth C) of a diamond really comes into play here as some diamond cuts will appear larger than others when compared like for like with the same carat weight.
This means the carat weight of a diamond is not always the best indicator of the size of a diamond. Diamonds are also measured in millimetres so if you want to know how big a diamond is this is a much better indication. Natural diamonds are increasingly rare the larger they are, so the higher the carat weight of a diamond the more expensive it is. It’s worth knowing at certain weights the price will jump, so for example, a 0.97ct diamond will usually be less expensive than a 1ct diamond of the same quality, even if visually they look like the same size.
Image 2 - Carat weight in relation to round brilliant cut diamond size, GIA website
Clarity
The clarity of a diamond is how free of inclusions and/or external blemishes a diamond is. The clarity of a diamond is inspected under 10x magnification. Examples of inclusions include small fissures inside the diamond or small crystals, while external blemishes may be things like chips or naturals (remnants of the original natural diamond crystal that remain after the diamond has been cut).
The scale starts with Flawless (which means there are absolutely no inclusions or blemishes in the diamond even under magnification) to Included (which means the diamond has inclusions easily seen with the naked eye and under magnification). Inclusions are not always a bad thing as they are unique, like a fingerprint, and act almost as a history of your millions (if not billions) of years old diamond. However, the fewer the inclusions, the more valuable the stone is. This is generally because the more inclusions a diamond has, the more they may interfere with a diamond’s ability to refract the light beautifully and give that perfect sparkle diamonds are known for. Speaking of which…
Image 3 - GIA Clarity Diagram Examples, GIA website
Cut
Diamonds are known for their sparkle. The fourth C refers to cut, which most people think refers to the shape of the diamond. This is true but it also refers to how well the rough diamond has been cut and polished to maximise its sparkle. When grading a diamond’s cut, a grader will also look at three factors:
- Symmetry (if the shape and facets are symmetrical)
- Polish of a stone (if the surface has any marks on it and if the facets line up perfectly)
- Proportions or cut (if the diamond has been cut to the right proportions so the light is being refracted perfectly)
Modern round brilliant cut diamonds have been designed to completely reflect all the light that enters the diamond back out to the viewer with both white light and refracted light (light split up into colours of the rainbow). If a diamond isn’t cut well the light that passes through the diamond will not all be reflected and therefore the stone will not sparkle as much.
You can see in the image below the difference between cut grades, from Poor on the left to Excellent on the right.
Image 4 - Cut grade examples. Photo: Kevin Schumacher/ GIA
Which of the Four Cs is the most important?
None of the 4 Cs should be taken in isolation when buying a diamond and all are important in different ways. When choosing a diamond, you should pick a stone that you love and is the perfect combination of all these factors for you. The way you balance the Four Cs really depends on what your priority is: whether that’s budget, size, or quality.
Having said that, a well-cut diamond will always result in a more sparkly diamond. Even the largest, whitest, and cleanest diamond can be ruined by a poor cut, making it look dark or glassy. Since cut is one of the 4 Cs that generally has the biggest impact on a diamond’s beauty but smallest impact on the cost, we would always suggest buying the most beautifully cut diamond that you can.
You may have come across jewellers talking about a 5th C for character. They're really just talking about that "je ne sais quois" that one diamond may have for you over another. It's not an exact science so it never comes on any diamond report, but you will find that by looking at diamonds in person, you will get an idea of what speaks to you.
If you would like some more advice, get in touch below.
