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The Four C's – Cut, Colour, Clarity and Carat

Brillian have their very own gemologists that inspect each of the diamonds that are set in our diamond engagement rings. We grade them according to the four universally accepted diamond characterisitcs; Cut, Colour, Clarity and Carat. Also known as the four C’s. It is the combination of these four characteristics that determines the value and desirability of the diamond.

We appreciate that not everyone knows lots about diamond rings, so here is a quick and easy-to-understand guide to the Four C’s:


A skilled diamond cutter is able to turn the raw diamond (a rough nugget) into a stunning gem by carefully working on its shape, style, proportions, symmetry and polish. It’s interesting to note that the cut of a diamond is the only element of this natural product which can be affected by man. When carefully completed, it is the cut of the finished diamond that gives it its sparkle, or 'brilliance', and fire, the rainbow-like colours you can see in a diamond.

A symmetrically cut diamond bounces light around internally between the facets, rather like a prism in front of a mirror, before returning the light back through the top of the diamond. To achieve optimum brilliance the pavilion depth, crown angle and table size must all be cut within a range of ideal proportions.


Diamonds are mined in a wide spectrum of colours – from colourless to some more unusual tints such as pink, blue, red, black and green. These are normally called 'fancy diamonds' due to their rarity.

Diamonds are graded by their lack of colour using an alphabetical system which starts at 'D' (colourless and extremely rare) all the way through to Z (tinted and relatively more common). People often think that all diamonds are colourless but in reality most diamonds in the normal colour range contain very faint tints of yellow and brown.


The clarity of a diamond is very important when considering its value. Clarity refers to the number, position and size of any naturally occurring inclusions (flaws) within the diamond. The fewer and less obvious inclusions, the more valuable the diamond is. The most important thing to consider when investing in a diamond is that any inclusions should not be visible to the naked eye.

Diamond clarity is graded according to the following scale after examination under a 10 x magnifying glass:


Diamonds are weighed in carats which is equal to 0.2 grams. This is divided into 100 points meaning a 25 point diamond is equal to a 1/4 (or 0.25) carat. The term carat is derived from carob seeds that were originally used to measure the weight of diamonds due to their remarkably uniform weight of 0.2 grams.

The carat-weight of a diamond is the easiest measurement to determine the size of it - most importantly, two diamonds can be of equal carat-weight, but their value can differ greatly due to their cut, colour, and clarity.

If you would like any advice about our diamonds or any of our diamond jewellery, please get in touch.