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The Four Cs

They're the hardest substance on earth. They're a girl's best friend. They're forever. In fact, there's an awful lot to say about diamonds. But at Mappin & Webb, we prefer to simply think of diamonds as a declaration - of love, of loyalty, of sheer, spontaneous happiness.

But before you go about choosing that perfect diamond, we think it's important you understand exactly what it is you're buying. So we've put together this guide to assist you as you start looking.

There are four main criteria to bear in mind, when buying your diamond. For convenience' sake, we call them the 'Four Cs'. These are cut, colour, clarity and caratweight (of course there is another C, cost, but we'll leave that for you to decide).


Diamonds are renowned for their ability to transmit light; the cut of the diamond determines its brilliance, dimensions and finish. A diamond that is cut to good proportions handles the light better, creating more brilliance and sparkle and, therefore, commanding a higher value. Transforming a diamond from its natural, rough state to a glittering, perfect jewel can take weeks, even months.

Measurements of cut quality include: Brightness, the internal and external white light that is reflected from the diamond; Fire, the scattering of the white light into myriad rainbow colours; Scintillation, the amount of sparkle that is produced, or the pattern created through light and dark areas.

Mappin & Webb diamonds are carefully considered and selected for their brilliance and undergo vigorous quality assessments.

Diamond Cuts

Types of Diamond Cuts


Clarity is graded based on the number, location, size and type of 'inclusions'. These are nature's birthmarks and are sometimes referred to as 'flaws'. Natural diamonds are the result of carbon exposed to extreme heat and pressure deep in the earth. It is this process which creates the 'inclusions' and 'blemishes' that characterise the diamond and thus contribute to its value.

Most diamonds contain miniscule inclusions that make each and every one unique. These inclusions neither mar the beauty nor endanger the durability of a diamond, although a stone will sparkle more the fewer and smaller the inclusions are.


Like all precious stones, diamonds are weighed in carats. Originally, they were measured with carob seeds, and this may be where the word 'carat' comes from. Later the system became more scientific, and one carat was standardised at 0.2 grams.

Fewer than 5% of diamonds used in jewellery weigh more than a carat. Most are weighed in hundredths of a carat, or 'points'. So 50 points is a half of a carat, or 0.50 carats.


The colour of a diamond is the final consideration when reflecting on the Four Cs. When we think of diamonds, we usually think of them as totally colourless. And, while these are the rarest and most valuable, they come in a whole range of other colours, like pink, blue or green. These are also very rare and, needless to say, very valuable.

We use the alphabet to grade colour. 'D' denotes colourless, and we move along the alphabet as any colour gets more visible.

The Four Cs

A look at Diamond Clarity, Carats and Colours

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