Know your sparkles: A guide to diamonds and the four Cs

If you’re looking to buy yourself or someone else some diamond jewellery, it really pays to know your stones. Knowing what you’re looking for can help ensure you get the best quality diamonds at a fair price.

You might think that identifying the quality of diamonds is difficult, but it is actually really easy once you understand the basics. The first thing you should know is how to grade diamonds, which is the four Cs of diamonds.

The four Cs are cut, clarity, colour and carat weight. While there are other ways that diamonds can be measured, these are the most basic and easy-to-understand. Other measurements also tend to fall under one of these four categories.


This is probably the most important aspect when it comes to analysing the quality of your diamond. However, it is also the most difficult category to understand as there are so many different diamond cuts available.

How bright and large a diamond looks is largely dependent on how it is cut. This means that two diamonds could be exactly the same weight but look as though they are completely different sizes because of how they are cut.

The cut of a diamond also refers to a diamond’s reflective qualities, as this also depends on the physical cut of the stone.

A good cut can be determined by the way light reflects when it enters the diamond. Ideally, the light should enter the top of the diamond – the table – before travelling to the next surface – the pavilion. Here the light should reflect to the other side of the pavilion and then back out of the table.

Badly cut diamonds will see the light leak out of the bottom or the side, making them seem less brilliant and much smaller than they actually are. The more brilliant your diamond appears, the better the cut and the higher the quality.


When talking about clarity, we mean how many inner flaws or inclusions – things like cracks, air bubbles and minerals that are not diamond – are visible within a stone. The fewer flaws present, the better quality the diamond and the more brilliant it will look.

Diamonds with a higher clarity – so fewer flaws – cost more money and are classed as higher quality stones. Stones with no flaws or inclusions at all are incredibly rare, which means they come with a sky-high cost.

There are classifications for diamonds that tell you what type of clarity they have; these are:
‘F’ flawless
‘IF’ internally flawless
‘VVS1’ and ‘VVS2’ very, very slightly included 1 and 2
‘VS1’ and ‘VS2’ very slightly included 1 and 2
‘SI1′ and SI2’ slightly included 1 and 2
‘I1’, ‘I2’ and ‘I3’ included 1, 2 and 3

When ranging from F to VS, the only real difference is on the diamond’s price as the clarity won’t affect the appearance of the stone to the naked eye.


The colour of a diamond is a big factor in choosing your jewellery as you ideally want a colourless stone so as to allow more light to reflect in it, creating a greater sparkle.

The only time you want a deeper colour, is if you are choosing black, yellow or other coloured diamond jewellery. Coloured diamonds are actually more valuable and are prized for their unusual shades.

When jewellers talk about colour affecting price, they are referring to white diamonds. While many diamonds may look totally colourless, stones that actually are entirely clear are very rare and incredibly expensive. This means that the whiter the diamond, the higher the cost.

Diamonds are classed on an alphabetical scale to denote how clear they are, starting at D, meaning an entirely colourless diamond. The scale finishes at Z, which will be used to classify very low-quality diamonds.

The further down the scale, the more yellow or brown diamonds will start to look, which means they will also absorb more light and look less brilliant.


The final C is carat, which means the unit of weight used to measure diamonds. As the size of a natural diamond increases, so does the price. This is because large diamonds are much rarer than smaller diamonds.

Carat is a different measurement from karat – commonly written as ‘ct’ – which refers to the purity of gold. Carat is always written out in full.

As well as being more expensive in general than smaller stones, diamonds that are of a larger size will also have a higher cost per carat. This means that even a carat difference can more than double the cost of a diamond when compared to a smaller stone of the same grade.

Most jewellery available to buy on the high street includes diamonds that are one carat or smaller, as larger than this comes at a very high cost. Larger carat diamonds can cost millions of pounds – Catherine Zeta-Jones’ ten-carat diamond engagement ring given by Michael Douglas is estimated at $2.5 million (£1.5 million) – which is why they tend only to be worn by the elite.

However, smaller diamonds can be just as beautiful, especially when included in gorgeously designed pieces of jewellery.

Now that you know the basics, you’ll be able to find gorgeous diamonds at good prices, especially when you are shopping with The Jewellery Channel. We have a complete range of stunning diamond jewellery that will fit everyone’s style and budget.

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