Last Updated June 2024


The 4Cs — color, clarity, cut, and carat weight — are the globally accepted standards for assessing the quality of a diamond. Learn more with these guides.

Unlock the Secrets of the 4’Cs of Diamonds

by Willyou.net * Sep 10, 2021

Key Takeaways

  • Cut, color, clarity, carat. These are the main things you have to consider when thinking about what diamond will be perfect for an engagement.
  • When a diamond comes out of the ground, it then has to be cut. This is about a lot more than the final shape – it’s about symmetry, proportion, length to width ratio, the arrangement, size and number of the facets…All of which are vital to the diamond’s light performance.
  • The Color, on the other hand, depends on how much pollution they have received underground. White diamonds are far more valuable if they show no signs of color.
  • In the same way, Clarity refers to the presence of inclusions (flaws), which ought to be avoided in diamonds destined for jewelry.
  • Lastly, the Carat is perhaps the least important aspect, as there is no “right” or “wrong” – although, for most shoppers, size is very important.
princess 4 prong halo engagement ring - The Four Cs of Diamonds

If there’s one thing you learn faster than anything else during your search for the perfect engagement ring, it’s that every diamond is totally unique.

Sure – from a distance, these stones have always seemed pretty similar to you. You know enough to know that, as far as investments go, diamonds aren’t exactly the cheapest – and that, when the time comes to propose, you’re gonna need one of your own.

From there, you have two approaches: you either head into your jewelry store and pick out the most expensive diamond you can afford, or you can learn about the Four Cs in order to make a much wiser investment into a diamond that will be just as (if not more) beautiful than the one with the higher ticket price.

The reality is that each diamond is distinctive, with its own ‘fingerprint’ and its own character, and the best way to understand it is to break it down into four categories. We’ll take you through the 4 Cs and explain each one, giving you the knowledge to choose the best diamond for you. 

What are the 4 Cs of Diamonds? 

Cut, color, clarity, and carat – the four features that have the greatest impact on the appearance of any diamond.

The system of evaluating diamonds on the strength of their Four Cs was developed by The Gemological Institute of America (more commonly referred to as the GIA, and considered to be the most reliable organization of its kind) back in the 1940s. It is now recognized around the world as the standard for grading and evaluating diamonds.

Before the GIA’s grading system came into being, the diamond industry was held back (to a certain extent) by a definitive lack of standards. The 4 C’s united these standards and ensured a unified approach for every gemologist, jeweler, and shopper. 

As a result, even newcomers to the diamond world can protect their best interests and make a very strong choice – one that not only fits their budget, but also maximizes it – provided they know how to interpret and use the Four Cs to their advantage…

Why Are the Four Cs Important?

For you, they ensure that you are able to judge the aspects of a diamond’s appearance that, while very important, can pass most of us by.

Gemologists and jewelers are experts in their field, and many of them will have decades’ worth of experience in studying diamonds up close – comparing one with another, and another – each and every day of their working lives.

For the rest of us, it’s true that diamonds can look pretty similar – but only at first. A little knowledge goes a long way here. You won’t need to spend hours upon hours poring over information – just a little time here and there getting to grips with these four vital categories.

Two of the Four Cs – clarity and color – refer to negative aspects that can encroach upon an otherwise beautiful diamond. These aspects need to be avoided as much as possible.

The other two – cut and carat weight – refer to more positive aspects: size and shape. They are equally important, but will need to be considered differently to clarity and color.

  • Cut
    • What is the GIA Cut Scale?
    • What is the Shape of a Diamond Called?
  • Color
    • What is the GIA Color Scale?
    • Is Color Important?
  • Clarity
    • What is the GIA Clarity Scale?
    • How is Diamond Clarity Graded?
  • Carat
    • How is Diamond Carat Measured?
    • How Much is a 1 Carat Diamond?
  • FAQ
    • What is the Most Important of the 4 Cs of Diamonds?
    • What is a GIA Diamond Grading Report?
    • Is it Worth Buying a GIA Certified Diamond?
    • Is it Safe to Order Diamond Ring Online?
    • Is There a 5th C?


Diamonds come out of the earth looking pretty rough – pun intended. They come out in irregular shapes, without that characteristic symmetry or polish that make diamonds recognizable to us. Only when they are cut and polished do they look beautiful enough to wear in fine jewelry.

Aside from carat weight, a diamond’s cut is arguably its most noticeable trait – and a little simpler to get your head around than clarity and color. For that reason alone, it’s one of the most important factors for you to get right since any shortfalls will be obvious to everyone.

GIA Cut Anatomy of Diamond - The Four Cs of Diamonds

What is the GIA Cut Scale?

Ideal, Excellent, Very Good, Fair and Poor

Diamond cutting is a highly exacting art. Cutters need to examine the natural shape and dimensions of the rough diamond in order to determine how to create the highest quality diamond possible, without losing too much of the original weight of the stone.

A diamond’s cut is by far the most significant factor influencing its fire, brilliance, and scintillation – or, in other words, its ability to sparkle as much as possible. Diamonds with a poor cut – for instance, one that is too shallow or asymmetrical – will not sparkle as well as it otherwise could.

To find a diamond’s cut grade, a gemologist will assess seven key components: brightness, fire, and scintillation – which, as we mentioned above, all relate to its light performance – as well as the more technical aspects of weight-ratio, durability, polish, and symmetry. 

Each of the 7 components are graded individually, although there is no singular way of combining them together to create one cut grade. The final grade will, to a certain extent, depend on the overall appearance of the diamond, which is why two diamonds can look totally different and still feature the same grade.

It is a little complicated, but provided you stick to the higher grades and work with your jeweler to understand the particulars of your chosen diamond, you can ensure a very high quality. 

What is the Shape of a Diamond Called?

Diamonds can be cut into many shapes, from the traditional Round to the fancy cuts, like the Pear, Heart and Oval, or the step cuts, such as the Emerald.

These days, many people use the terms ‘cut’ and ‘shape’ interchangeably, and that can be a little confusing at first.

While the GIA system for grading cut refers only to the quality of the cut (regardless of size), a diamond’s shape refers to its silhouette – arguably the most striking aspect, and the first thing you’ll notice when you lay eyes on it.


Of all the Four Cs, color is probably the first curveball you’ll come across. While there are naturally colored diamonds out there – known as ‘fancy colors’, and available in just about any hue imaginable – most of us want to stick to the colorless diamonds so characteristic of engagement rings.

Surely color doesn’t matter one iota when your sights are set on a clear diamond, right? Wrong – and a pretty risky conclusion to jump to.

What is the GIA Color Scale?

The GIA grades diamonds on a letter color scale from D – Z. The less color a diamond has the higher the value it has. A diamond graded with the letter D represents a colorless diamond and continues up the scale to a diamond with the letter Z representing a light yellow or brownish tint. Each diamond is color graded by using controlled lighting and precise viewing conditions. 

This particular color scale applies only to clear diamonds, with fancy color diamonds being graded against an entirely different scale.

In clear diamonds, it is very common for diamonds to be ‘polluted’ by other substances during their development underground. A high presence of nitrogen molecules can effectively pollute the diamond’s colorless appearance, and cause it to appear yellow or brown.

This may be a slight tint – not even distinct enough for the untrained, naked eye to discern – or it may be very, very obvious (or anywhere between).

A color grade is used to demonstrate how significant a diamond’s yellow cast is. There is very little distinction between one grade and the next (particularly at the higher end of the scale, where any yellow tint requires specialist knowledge, lighting, and tools to detect), so the scale is divided into the following categories:

GIA Diamond Color Scale - The Four Cs of Diamonds

Colorless diamonds (D-F) are, obviously, the most expensive. Near Colorless diamonds (G-J) are, however, still of a high enough quality to appear clear, particularly to the untrained eye. Below that, however, discoloration will be more obvious, and will impact the natural beauty of the stone.

Is Color Important?

Yes, as any visible yellow tint to your diamond could have a major impact on an otherwise beautiful engagement ring. Still, you don’t need to shoot for a D Color to make the most of your investment.

Remember how we said that there was very little difference between each separate color grade? While that may sound a little confusing right now, you’ll be glad you worked that one out when the time comes to hand over your hard-earned cash, since even an F Color diamond comes with a significantly higher price tag.

Still, when it comes to diamond color vs clarity, its clarity that falls a little higher on our list of priorities…


If you tend to think of gemologists as the guys with great big magnifying glasses, then you’re partly right. A big part of a diamond’s quality stems from the level of inclusions and blemishes it has and, to accurately measure those, diamond graders have to inspect every part of a diamond’s surface and internal structure under 10x magnification.

And, while it’s pretty unlikely that you’ll ever be looking at your diamond so closely, you still need to know exactly how the clarity grades impact the diamonds you are looking at.

What is the GIA Clarity Scale?

Flawless (FL), Internally Flawless (IF), Very Very Slight Inclusions (VVS1 and VVS2), Very Slight Inclusions (VS1 and VS2), Slight Inclusions (SI1 and SI2), Inclusions (I1, I2 and I3).

Inclusions are internal flaws, caused by natural forces and pollutants during the diamond’s long development underground. Most are far too small for the eye to see, although some can overwhelm a diamond and decrease its value by thousands of dollars. You can check out our guide to what diamond inclusions really are in order to get a better idea about what it is you’re looking to avoid.

Blemishes are external flaws. Some are natural, but many are caused during the diamond’s journey from the earth’s surface to while the diamond is being handled or worn. Again, these are usually too small to be seen by the naked eye.

When these inclusions and blemishes are small enough to go unnoticed without a microscope, a diamond is referred to as being eye clean.

Eye clean diamonds will, by definition, appear to be as flawless as FL and IF diamonds – and they can be found in grades as low as VS and, at times, SI. 

How is Diamond Clarity Graded?

It takes an expert eye and 10x magnification to accurately identify any and all inclusions and blemishes a diamond has.

The GIA clarity grading system takes in consideration the size, nature, position, color, relief, and quantity of clarity characteristics visible under this high level of magnification. 

These imperfections are then documented on a diamond ‘plot’, which, as you can see from the image below, offers a map to a diamond’s inclusions. This plot is included in every single GIA Diamond Report, and represents a unique ‘fingerprint’ for the diamond.

Only Flawless Diamonds will have no inclusions marked on their diamond plot. Although it is inevitable that they will still have inclusions, they may not even be visible under 60 or 100x magnification.

GIA Diamond plot Clarity Characteristics - The Four Cs of Diamonds

As with color, there is only a minor difference between one grade and the next – particularly in the case of degrees, such as VVS1 and VVS2. Here is a brief explainer on the separate grades:

  • Flawless (FL) – No inclusions or blemishes are visible to a skilled grader using 10× magnification
  • Internally Flawless (IF) – No inclusions and only blemishes are visible to a skilled grader using 10× magnification
  • Very, Very Slightly Included (VVS1 and VVS2) – Inclusions are difficult for a skilled grader to see under 10× magnification
  • Very Slightly Included (VS1 and VS2) – Inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification
  • Slightly Included (SI1 and SI2) – Inclusions are noticeable to a skilled grader under 10x magnification
  • Included (I1, I2, and I3) – Inclusions are obvious under 10× magnification and may affect transparency and brilliance.


Remember how we said that cut is the most noticeable part of the diamond, second only to carat weight? This is because carat weight refers to the diamond’s size – although, obviously, two diamonds of the same carat weight can look significantly different in size if they are cut differently.

For instance, this 0.7 Carat Round Diamond can appear a little smaller than this 0.7 Carat Pear Diamond, since the latter boasts an elongated shape.

How is Diamond Carat Measured?

1 carat is equal to 0.2 grams, or 200 milligrams. GIA gemologists use an electronic micro-balance to weigh each diamond to gather the carat weight.

1 carat is approximately the weight of a paperclip – or, perhaps more poetically, a raindrop. A carat is divided into 100 points. So, a 50-point diamond weighs .50 carats. 

The first step in the GIA certification process is weighing and measuring the diamond. GIA gemologists use an electronic micro-balance to weigh each diamond to gather the carat weight. They also use an optical scanning device to determine the exact measurement and proportion of the diamond. These devices provide the most accurate measurements of a diamond. It’s very important that a diamond’s carat is recorded precisely by the grader, since even the most minor discrepancy in weight between two otherwise identical diamonds can cause the price to change drastically.

Of all the Four Cs, carat is unique in the fact that there is no ‘optimal grade’. The average engagement ring diamond sits at around 1 carat, although recent years have seen many shoppers preferring larger diamonds around the 2 and 3 carat ranges. The largest cut diamond in existence is 530.4 carats (the Cullinan 1), and far too large to be worn on the finger – not to mention it belongs to the British Royal Family.

What we’re trying to say is this: there is no ‘right’ carat weight, although we would tend to advise shoppers to stay above the 1 carat range to ensure a beautiful, eye-capturing ring.

How Much is a 1 Carat Diamond?

Anywhere from a $2,000 to $12,000 – or, in some rare cases, even more.

While it would be simpler, it would be impossible for any diamond’s value to be determined by carat weight alone. Each of the Four Cs influence that final market value, which means that a one carat diamond (or, for that matter, a two, three or ten carat diamond) has a very broad potential price range.

When it comes to good quality diamonds, price tends to increase exponentially with carat weight. In other words, this 2 Carat H-SI2 Round Diamond won’t simply cost double the price of this 1 Carat H-SI2 Round Diamond. This can represent something of a sticking point for some shoppers, and it can make it slightly harder to get your head around the types of diamonds available in your price range, but it’s an important factor to keep in mind at all times.


What is the Most Important of the 4 Cs of Diamonds?

Most professionals in the diamond industry consider the cut of a diamond to be the most important of the 4 Cs. The cut of the diamond has the greatest influence on a diamond’s sparkle. And, while it’s true that all 4 Cs are important in collaboration, the cut is definitely a major player. 

The second most important C of the 4 C’s is the diamond’s clarity and, following closely after that, color. Both the clarity and the color of a diamond play such a huge role in the stone’s value – and, more importantly to you, its beauty.

In both instances, you’ll want to aim for eye cleanliness. A diamond with no inclusions, blemishes or discoloration that are visible to the naked eye will be as beautiful as one that is flawless, while costing potentially thousands of dollars less.

By this logic, carat is the least important – primarily because, as we mentioned above, there is no ‘right’ or ‘wrong’ carat weight.

Look at it this way: if you focused primarily on carat weight then, even on a budget of around $10,000, you could find a very large diamond indeed. But at what cost? In all likelihood, eye cleanliness will be impossible, which means your above-average diamond will feature visible inclusions, a strong yellow tint and, potentially, a pretty poor cut.

Focus on the other Cs first, then increase the size of diamonds you’re looking at until you reach the boundaries of your budget.   

What is the Least Important C in Diamonds?

While none of these features can be overlooked, clarity is the least restrictive of the four categories.

Yes, eye cleanliness remains key – this isn’t your sign to loosen the reigns and invest thousands of dollars into a diamond with visible inclusions. Instead, we’re saying that, since it is entirely possible to find a diamond with a clarity grade as low as SI1 (or, in the cases of smaller diamonds, SI2), you’ve got plenty of ‘breathing space’ when it comes to budgeting for an eye clean diamond.

As we mentioned above, cut is inarguably the most important factor, since it determines the extent of a diamond’s sparkle.

Nevertheless, don’t let one (or more) of these Cs slip from your radar – they’re all vital considerations.

What is a GIA Diamond Grading Report?

Arguably the most reliable document a diamond can be accompanied by. It confirms that the diamond has undergone stringent checks, according to the scales for cut, color, clarity and carat weight listed above, conducted by experts.

Each diamond is analyzed and graded by at least two gemologists, based on these four qualities. Every diamond that completes the GIA grading system and receives a complete assessment of the stone’s 4 C’s receives a GIA certification grading report, with a unique GIA Report Number.

You should never invest in any diamond that does not come with an authentic GIA Report. Unfortunately, some people do attempt to forge these reports and pass off a low quality diamond as one that is much more valuable – or a fake diamond as a real diamond.

For peace of mind, you can verify the authenticity of any report via our GIA Diamonds Grade & Score Check using the unique Report Number.

gia report sample - The Four Cs of Diamonds


Is it Worth Buying a GIA Certified Diamond?

Absolutely. We would strongly urge any of our readers to invest only into diamonds with a valid GIA Report.

We’ve said it before, and we’ll say it again: the best level of reassurance you can take from your diamond is its GIA Report.

Reputable jewelers will never try to sell you a diamond without this vital document, so don’t hesitate to walk away from anyone trying to sell you a diamond that has not been graded and certified by experts.

Is it Safe to Order Diamond Ring Online?

No – even if it is accompanied by a GIA Report, there are still too many risks involved for this high value investment to prove wise over the internet.

If there’s one thing the Four Cs demonstrate beyond a shadow of a doubt, it’s the fact that every diamond is totally unique. Even two diamonds with very similar grades can look noticeably different to one another – although you might not be able to put your finger on how.

Images are great for research. It can help you decide what sort of shape, size, and style you’re aiming for, and which ones you can resign to the ‘No’ pile. But, even then, you can’t replace the security of going into a reputable establishment and actually seeing that diamond in person – learning the way it sparkles under the lights, and how it looks up close and personal.

So, even if we ignore the potential security risks of getting a diamond mailed to you – after all, plenty of online vendors offer secure ways of shopping – it’s still a risk. You can’t be sure that diamond is The One until you actually see it.

Is There a 5th C?

Not officially, although some people consider an unofficial fifth C – Confidence – to play a defining role in any good diamond choice.

For around eighty years, the GIA has maintained the standard for establishing and understanding diamond quality. It has, in a sense, created a common language that gemologists, jewelers, collectors and shoppers can all comprehend, meaning that it is much easier to make sure that everyone is kept on the same page.

Still, for the average shopper looking for the perfect diamond to put on the finger of their future bride, it takes more than the Four Cs alone to make a good decision. It also takes a great amount of confidence in the choice you are making.

On the one hand, you have to have confidence in your own ability to understand your partner, and work out exactly what she wants to see when you finally get down on one knee and draw back the lid of the ring box.

On the other hand, you need to be able to have a great deal of confidence in your jeweler. While you can (and should) do your research beforehand, some things only come with many years’ experience – and having a reputable jeweler by your side will ensure the perfect complement to your understanding of your bride-to-be.

At WillYou.Net, we have amassed an impressive network of jewelers working across the United States – all of whom we have personally done business with in the past, and have met our high standards for customer care. That way, you can feel sure about putting your confidence into another’s hands – and finding the perfect ring for your future bride.

To learn more about GIA grading or the 4 C’s of a specific diamond, check out our new GIA Diamond SEARCH ENGINE! You can now search your diamond and compare from over 2,000,000 GIA diamonds, all of which have been scored by our team of experts against the GIA’s rigorous grading method.