When choosing a diamond, one of the most common phrases you will hear are the "4 C's" - cut, colour, clarity and carat. They form the universal language of diamond grading, the framework used to describe a stone's quality and character.
Understanding the 4 C's isn't about memorising a certificate - it's about appreciating what makes each diamond unique, from the way a well-cut stone catches the light to how carat and clarity tell the story of its journey. In this article, we'll walk through each of the four C's and what they mean for the diamond you choose.
The 4C’S of a (white) colourless diamond: Cut, Colour, Clarity & Carat
One of the simplest ways to determine if a diamond appeals to you is by simply taking a close look at the stone in different light conditions (indoors, in the shade and in natural sunlight). Gradually tilt the diamond back and forth, and side-ways and observe how it reflects light back and sparkles. What your eyes see is a sparkling diamond, will differ from what someone else thinks is a sparkling diamond. That is because human eyes are unique and each pair of eyes see beauty and sparkle differently.
So, without getting too confused about the technical jargon of grading a diamond (‘the 4 C’s’), just observe the diamond and see if it is “talking to you”.
For those who are technically inclined and prefer to understand industry terminology of grading a diamond, the following is a brief summary of the 4 C’s of a diamond. This a guide for informative purposes only, it is not meant to be a substitute for professional advice of a trained diamond grader or valuer.
CUT
There are many in the industry who would probably rate diamond cut as among the most important of the 4 C’s. A diamond is the hardest of all gemstones, made of carbon (primarily through volcanic processes) and it has the highest refractive index of all gemstones too.
What that means, is if the diamond is well cut to precise proportions, it will reflect and refract light significantly and that makes it sparkle. If on the other hand, it is cut too shallow or too deep, light entering from the top of the stone will not reflect back from the top, but will leak out from the bottom of the stone. These are poorly cut diamonds and will not sparkle as much as a well-cut diamond.
Image: Courtesy of GIA
COLOUR
When referring to ‘colour’ in a colourless (or white) diamond, we are in actual fact referring to the “lack of colour” or how “colourless” is the diamond? A trained professional (diamond grader or valuer) will grade colour from the bottom of the stone. The more “colourless” the diamond (D – E colours), the higher the value of the diamond. F, G and H are deemed as “high white” diamonds and the lower you go from there on you will observe a yellowish – brownish tint in the stone, thus reducing the value of the stone. This is not referring to the grading of colour in coloured diamonds like Champagne, Cognac, Yellow, Pink and so on.
Image: Courtesy of GIA
CLARITY
All diamonds have some level of natural inclusions in the stone. A diamond is basically solidified carbon and in the process of evolving under-ground due to enormous pressure of heat, it is normal that a stone will contain an amount of natural inclusions. These are not “flaws” in the diamond. But the greater the number of inclusions, the lesser the value of the diamond. The important thing with determining clarity in a diamond is whether or not you can see any inclusions in the stone with the naked eye or do you need a 10x magnifying loupe to see them? Do not select a stone if you can view the inclusions with the naked eye.
Image: Courtesy of GIA
Some cultures deem the lack of inclusions in a diamond as a symbol of purity. Therefore, they are willing to pay a premium price for diamonds with negligible or no inclusions (Internally flawless, Very Very Slight (VVS) and Very Slight (VS) clarity grades.
CARAT WEIGHT
Diamonds are cut for weight. The heavier the diamond (whose weight is determined in Carat’s), the more valuable it is. Imagine a rough piece of diamond (the size of a fairly large stone). The planner will cut diamonds out of the rough in a way that minimises the wastage remaining after cutting. For some people, size matters. The bigger the size, the better. So, a diamond is cut to maximise weight (as opposed to maximise sparkle) because cutting for weight can cause leakage of light through the bottom of the stone.
To find a diamond with the best of all the 4C’s is a rarity and a very expensive process too. Unless you are a diamond connoisseur, investor or collector of fine diamonds, it is often the case that there is some level of trade-off: Colour or Clarity, Cut or Carat Weight that will influence your buying decision.
It is precisely for this reason we recommend that you should observe the diamonds with your own eyes and see if it appeals to you. Remember, you will be wearing the diamond for a long time, and there is no point in buying a stone if it is not attractive to your eyes.
The 4Cs of the diamond will be confirmed to you by the independent diamond grading certificate which the seller will give you. Use this certificate to re-confirm what you have been advised is the quality of the diamond by the seller.
Together, cut, colour, clarity and carat form the foundation for choosing a diamond with confidence. The numbers on a certificate are only tell part of the story.
Image: Victoria era sterling silver floral brooch, set with diamonds.
Ultimately, the "right" diamond is the one that speaks to you: the way it catches the light, the way it sits against your skin tone, the feeling you get when you see it. A grading scale cannot capture that, and it's worth trusting your eye as much as the specifications.
If you're still weighing up your options, or simply want to understand a stone a little better before you commit, our expert staff are always here to guide you and answer any questions. Book an appointment or drop into our showroom and we will happily guide you through the 4 C's in person, answer any questions, and help you find a diamond that feels every bit as special as the occasion it marks.