What are the 4 C's of a diamond? A general buying guide

Posted by Paul Milligan on


When it comes to a stunning piece of jewellery or the ultimate symbol of love, the design of the engagement ring is frequently the focus.

Along with an excellent design, it's the quality of the diamonds that plays a vital role in the sale and ultimate value of your jewellery. Carat, clarity, colour, and cut, or “the 4Cs”, are the measure of a diamond's quality and value. 

Notably, the 4 Cs are used to evaluate both lab-grown and mined diamonds. 

Diamonds have a wide range of characteristics. A brief examination of two diamonds of the same size, for example, might suggest that they’re worth the same amount. This isn't entirely correct because even if there are tiny differences, a diamond's effect and value are different. 

Carat, clarity, colour, and cut are the 4 C’s in the diamond. They’re the four most well-known criteria for identifying a diamond's quality and worth. 

What is a Diamond?

Although most people are familiar with the phrase ‘diamond ring’, few know what a diamond really is or where it comes from.  Prosperity, beauty, immortality, and power are all associated with these natural minerals.

These glittering jewels have captivated us for millennia. Pure diamonds consist solely of carbon atoms and the stones formed millions of years ago deep in the planet's interior when the carbon atoms fused together in a tight regular pattern to create a crystal lattice under pressure and heat.

These gemstones only reach the planet's surface during volcanic eruptions.

Rough diamonds can only be found in volcanic rock. As a result, they are rare and come from the planet's core. 

It’s what sets the ‘pressed carbon’ apart. Diamonds are the world's hardest natural substance. Because of this property, they are used in the toolmaking industry and in science and medicine.

Diamond Ring by Alexander David London Avant Garde Jeweller

What is the significance of buying a diamond ring?

Diamonds can last forever. Thus, they're the perfect emblem for a ring that symbolises eternal unbreakable love.

The custom of giving a ring as a wedding or engagement gift stretches back to the Middle Ages.

Giving your beloved a diamond ring as an engagement ring has been a long-standing custom, especially in the United Kingdom. In Germany however, both partners are likely to wear engagement rings.

Which of the 4Cs is the most important?

In this guide, we’re not going to take sides because all the 4C’s of a diamond work together.

Having said that, it’s worth mentioning that the cut quality of a diamond is crucial since it determines whether the stone is proportioned and bright.

The cutter’s skill is vital here. The cutter uses skills to blend the proportions of the diamond so that light circulates inside the stone, and fully reflects back out.

The cut quality influences the weight, color, and clarity of a diamond, 

The 4Cs at a glance:

Carats = weight

Clarity = Purity

Colour = colour

Cut = proportions and finish

The 1st C is CARAT 

If you’re buying a diamond ring, for instance, remember that the carat (ct) is a unit of weight used around the world.

When it comes to diamonds, the rule of thumb is that the larger, rarer, and more precious a stone is, the more carats it weighs. 

1 carat is equal to 0.20 grams. The majority of diamonds are 0.20 to 15 carats in size. 

When purchasing a diamond, the carat weight is an important factor to consider. The more carats a diamond has, the more valuable it is. 

Although this is the most well-known attribute of a diamond, it is often confused with its size. 

Also, don’t forget that not every lab-grown diamond is identical to those found in nature. When it comes to size, though, it can be tough to tell them apart. 

As a result, a diamond's worth is determined, among other things, by its weight. 

A carat is made up of 100 points. A 25-point diamond, for example, weighs 1/4 of a carat, or 0.25 carats. The weight of a carat can be measured to the thousandth of a carat with a good carat balance (weighing scale). 

You also have to know that the carat weight is one of the most significant metrics in determining a diamond's price. But it is far from the only one. 

Because the price of a diamond is also determined by the value of the other elements that make up the 4Cs, two diamonds of the same weight will not always have the same value.

The carat weight of diamonds was changed to the metric system around the turn of the twentieth century, and the use of a 10x magnifying glass for determining clarity and reference stones for colour grading of a diamond is now the worldwide standard.

The diamond's weight and size are inextricably linked; thus, the weight is calculated from the size (diameter) and vice versa. 

Originally, a carat was defined as the weight of a dried carob kernel. The seed core weighs about 0.2 grams, which is the same as about 1 carat of diamond.

 Diamond Ring on a finger by Alexander David London Avant Garde Jeweller

The 2nd C is CLARITY 

You will need to consult an expert to determine the clarity of a diamond.

Alexander Davis Jewellery uses magnifying lenses to study stones, which magnifies the diamond's interior tenfold. If no contaminants are found under these conditions, the stone is considered ideal. 

Most diamonds have inclusions, which are like birthmarks. Although these are considered flaws, they can add to the character of the diamond.  It’s a natural mineral afterall. 

You can determine the clarity of a diamond using a magnifying glass loupe with a 10x magnification. The diamond's lack of apparent inner characteristics is called ‘flawless’.

However inner diamond qualities can aid in the creation of a diamond's individuality. Interior features have an impact on the beauty and uniqueness of a diamond. 

The diamonds we use at Alexander Davis Jewellery are normally certified by an international laboratory like the Gemmological Institute Of America (GIA).  They come with a certificate detailing the 4 C grades that they have determined.


 The 3rd C is COLOUR 

The third of the four Cs is colour. Diamond grading experts assign a letter to the stone based on this criterion, ranging from D to Z. (D being the highest grade and Z the lowest). 

White diamonds, according to experts, range from D to H. The stones become yellowish as the colour level increases. 

That's not all! The colour classification, which begins with the letter D and concludes with the letter Z, determining the tone of the stone. 

Colorless diamonds in the D-F range are regarded as more valuable. The reason is that as the stone turns yellow, the scale drops, and the price drops with it. 

The hue of a natural diamond is usually determined using a scale synonymous with white. Most purchasers perceive natural diamonds as white, yet they are often tinted with yellow or brown.

The rarer and more precious a stone is, the closer it is to superb white. Natural diamonds are rated on a colour scale ranging from D, excellent white+, to Z, very dark, tinged with brown or yellow. 

Diamonds come in almost every colour due to natural processes that occur within the Earth during its formation.  Diamonds that are pink, yellow, blue, and green, and are among the most valuable and sought-after stones in the world.

The reality is that since these natural colours are so rare, their value is limitless. They're evaluated using a colour grading method that describes visible colour accurately.    

Diamond by Alexander David London Avant Garde Jeweller

The 4th C is CUT 

As you may know, nature determines the first three requirements of the 4Cs, but it is man that determines the cut. 

The term "cut" can relate to the stone's shape (its appearance) and the cut style. Let's call it the arrangement of the facets on the stone. 

The cut quality of a diamond has a significant effect on its brightness and visual impact. 

The diamond can take on a variety of shapes to show off its brilliance and uniqueness. The most popular jewellery shapes are the round and princess cuts, though we work with many other beautiful cuts including radiant, Asscher, emerald, marquise, oval, and old-cut.

The quality of a diamond's cut determines its brightness, regardless of its shape.

It is the only one of the four-diamond grading criteria that is based on a human’s interpretation. Indeed, a small diamond can cause excessive rough diamond loss or ineffective utilisation of the diamond's brilliance. 

A well-cut diamond can create impressive light effects that emphasises three main characteristics:

The dispersion of light across the complete range of hues is often called refraction.

The brilliance of a diamond refers to the total amount of light reflected by it.

There’s something you need to watch out for if you want to buy a quality diamond:  when you move the diamond, you'll see flashes of light or reflections.

To appreciate the cut of a diamond, you must first identify its shape. The most popular cut is the round bright cut, which comes in many shapes and sizes. Diamonds in unusual forms are known as "fancy" shapes.

A diamond's proportions are the relationship between table size, crown angles, and total depth. Variations in these proportions will impact the diamond's interaction with light.

So that is our summary for the 4C’s of diamonds. If you would like to discuss any diamond ring with us, then please contact us. We would be happy to work with you to help you to create your dream piece of jewellery or to talk through all the different design ideas that we have.

Our expert designers will guide you on each step of the process and provide you with images to help you realise your dream ring.

If a bespoke engagement ring is something that you’re interested in take a look at it in more detail here or contact us for further information.





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