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Diamond Guide: The 4 'Cs'


Cut is the factor most involved in determining the sparkle of a polished diamond. Cut is expressed in terms of the brilliance, fire and scintillation of a diamond. To maximise sparkle, a diamond must be cut to very specific parameters of angle and dimension with a strict attention to the polished finish of the diamond. It is the cut of a diamond taht truly gives the diamond its life.

Cut grades were developed by the GIA (Gemmological Institute of America) during the 1940's and 1950's to enable independent labs to not only evaluate clarity and colour but to check the structure of the diamond itself. A round brilliant cut diamond will have 57 or 58 facets which are precisely cut and defined. While these are miniature in size they are extremely important as they govern how well the diamond is going to sparkle.

Cut Grades

Excellent - The excellent cut is one of the most valued and cherished cut grades. This cut reflects almost all the light that enters the diamond. In some cases when an excellent cut diamond is reflected such a large amount of light it can be upgraded to the rarer 'Ideal Cut'. Only exceptional stones are given this grade.

Very Good - A very good cut will not reflect as much light back as an excellent cut however this grade will only loose a small percentage of light giving your stone a fantastic fire. These stones are a fantastic purchase and prove to be stunning value.

Goodcheaper than a very good or excellent cut. Fair-The fair cut will still sparkle but when compared to any of the higher grades you will see a difference in the sparkle of the diamond. If buying a higher grade stone in a larger carat weight however you can find some very good priced diamonds. Still worth a look!

Poor - Most of the light will not be reflected back out of the diamond. These stones are usually too deep or shallow to be able to reflect the light back out.


The clarity grade a diamond is given is determined by the degree to which these natural features are visible at 10 times magnification and the number, type, colour, size and position of the features in the diamond. ‘Skin blemishes’ are surface features like scratches and nicks. ‘Inclusions’ are naturally occurring features in the diamond such as tiny fissures or feathers and included crystals which can be diamond or other minerals. Diamonds without features are rarer and so more expensive, but small inclusions do not affect the beauty or the brilliance of a diamond. Diamonds equal in weight, colour and cut will vary greatly in price depending on their clarity features. The internationally accepted system of grading divides clarity into five distinct groups:

1. Flawless - Internally Flawless – the rarest of rare diamonds, known as Flawless (FL) diamonds are those with no internal features and no external features or blemishes visible at 10 x magnification. An Internally Flawless (IF) diamond will also have no internal features, but may exhibit a minute scratch left over from polishing.

2. Very Very Slightly (VVS) Included diamonds are those with minute inclusions so small that they are extremely difficult for even a skilled diamond grader to see at 10X magnification. A VVS1 diamond may have a single pinpoint, whereas a VVS2 may have a pinpoint and a tiny needle-like crystal of another mineral as its internal features.

3. Very Slightly (VS) Included are those diamonds with minor internal features deemed difficult for a skilled grader to detect at 10X. A VS1 diamond may have a tiny cloud of inclusions, or a pinpoint or two, whereas a VS2 diamond could have, for example, a small included crystal.

4. Slightly Included (SI) diamonds are those with internal features that are easily seen at 10X magnification. Divided into SI1 and SI2, even an SI2 diamond may contain internal features that are still not visible to the unaided eye.

5. Included (I-1, I-2, I-3) diamonds are those with features that can be visible to the unaided eye and may even affect the durability of the diamond.


Diamonds occur naturally in all colours of the rainbow. Generally, the rarest diamonds exhibit no colour at all (apart from fancy colours). Polished diamonds are graded for minute variations in depth of colour, from ‘colourless’ to ‘light colour’. This is universally known as the D (meaning ‘exceptional white’) to Z (‘tinted colour) colour scale.

A common misunderstanding with colour grading is that in fact what the colour grading is referring to is the lack of colour in the diamond. For example a K colour diamond is going to be a light yellow while a D colour will be colourless or 'white'. The colour scale goes from Z being the lowest and D being the highest. We use a minimum of a G colour, although we can supply stones in H colour and up to a D colour if required. Fancy coloured diamonds such as a blue, yellow, pink green can be specially sourced if needed.


Carat is a measure of metric weight. One carat (1 ct) equals 0.20 grams and is divided into 100 points (half a carat - 0.50 ct - diamond can be described as a 50 points diamond). It is important to remember that a diamond is not valued simply by carat weight alone and two diamonds of equal carat weight can have very different values, depending on cut, clarity and colour.