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Choosing a Diamond

What do the 4Cs really mean? See how you can buy beautiful diamond without breaking your budget.

Once you fully understand the diamond 4Cs, you can use them to your advantage, learning how to prioritise these key criteria you can choose a diamond Just right for you.

That grade is made up of four factors, often known as the 4Cs:

·         Cut

·         Clarity

·         Colour

·         Carat weight

Each “C” has its own grading scale for evaluating quality. Put together, the diamond 4Cs help diamond sellers determine price and compare diamonds to one another. They’re also a useful tool for shoppers — and the more you understand about them, the savvier you’ll be in choosing your diamond!

Why the 4Cs matter

When you shop for a diamond, you may see a string of letters and numbers that indicate the diamond’s grade. It might look something like this:  1ct E VS1. Diamond experts will tell you that’s a very nice diamond — and probably a quite expensive one.

Demystifying the 4Cs


Diamonds are also measured in carat anything below 1ct is often described at points, 100 points equals 1 carat. The abbreviation "ctw" standards for “carat total weight,” which measures the total weight of all diamonds in a piece of jewellery.

Very small differences in carat weight can sometimes result in a disproportionate cost. To the eye, the difference between a 1.1ct and 1.2ct diamond might be impossible to discern, but the cost difference between can be thousands of pounds for otherwise visually identical diamonds.

So in simple terms look for a size you like and think of the width in mm and if you can find a shallow cut diamond you may save £££’s of “invisible” carat weight.


Diamonds come in many different colours. The market has traditionally values the whitest diamonds higher than others, and the grading scale reflects that. The D grade, at the top of the scale, is considered “colourless,” rarest and most expensive. Going down the 23-grade scale from D to Z, diamonds become progressively more yellow, brown or grey.

Most diamonds sold for jewellery today are considered “near colourless” — between G and J on the colour scale. At a J grade and beyond, the human eye can start to detect a yellow tint.

A D-colour diamond is a rare specimen — and it costs huge sums – frankly unless you are a millionaire it’s unnecessary. Moving down the colour scale toward H and I allows you buy a diamond that still appears white to the naked eye, and it usually significantly more affordable. J and lower you might if you have great eyesight begin to see colour differences.

The exception to white diamonds are “fancy” diamonds, often driven by fashion “fancy” coloured diamonds, when they occur naturally, are rare and very expensive. Just as good can be colour treated diamonds which look great to the naked eye and help you afford these much coveted colours for significantly less.


Diamonds are naturally created over millions of years and like most natural things, they’re rarely perfect. Like any rock or mineral, diamonds often have flaws, known as inclusions and blemishes. Diamond cutters try to cut and polish a diamond to hide these inclusions or work around them, but they’re still there — and the clarity grade measures them. The scale ranges from flawless to heavily included:

F (flawless inside and out)

IF (internally flawless, which means there are blemishes on the surface but not inside the diamond)

VVS1 and VVS2 (very, very slightly included – two levels)

VS1 and VS2 (very slightly included – two levels)

SI1 and SI2 (slightly included – two levels)

I1, I2 and I3 (included – three levels)

It may be difficult to see inclusions with the naked eye unless you look closely, depending on where they are located within the diamond. But every diamond is different, so you have to look for yourself. If you look at an SI2 diamond and personally can’t see the inclusions without a jeweller’s loupe, you can probably accept a lower grade and save on cost without compromising beauty.


Cuts can vary from diamond to diamond and have to do with how the diamond cutter chooses to shape, facet and polish a diamond. Sometimes diamonds are cut so they’re heavier, thus fetching more value for their carat weight; sometimes they’re cut to hide or minimize inclusions.

But many diamond companies are focused on cutting diamonds for beauty. A diamond is essentially a prism of light, and diamond cutters work to let the most light shine through each stone. When done well, a diamond’s cut can be the most important C. When grading the cut of a diamond, laboratories evaluate the diamond’s:

·         BRIGHTNESS - The light that reflects from the diamond.

·         FIRE - How the light scatters through the diamond to create a rainbow of light, like a prism.

·         SCINTILLATION - The amount of intense sparkle or flashes that occur across the surface of the diamond as it moves under light.

Diamond cuts are often evaluated as:

·         Ideal or near ideal (meaning that the angles and proportions of the diamond have been cut to produce the ultimate brightness, fire and scintillation)

·         Excellent

·         Very good

·         Good

·         Fair

·         Poor


Making the Cs work for you

Now that you understand the diamond 4Cs, you can use them to your advantage. As you are comparing diamonds and trying to work within your budget, consider how you might:

Get a beautiful, sparkling diamond by focusing on cut while sliding down the scale a few levels on colour and clarity.

Get a larger diamond but scale back a fraction of a carat (10-20 points) to save money.

Buy a lower-weight diamond but a near-ideal or ideal cut, focusing on the diamond’s radiance and beauty and putting less emphasis on the size.


The 4Cs will reassure you that you’re buying a quality diamond and getting what you pay for, but remember that they’re really just a tool. Rather than showing off about your 1ct. E VS1 diamond, lets the diamond talk for you “Look at my beautiful diamond ring!” And that’s ultimately what matters most.