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Diamonds Explanation of the 4 Cs

We at Thatcham Jewellers have been offering fine jewellery to our customers over the years and have earned a reputation for style, quality and knowledge. We realise that the more customers know, the more they will have confidence in their choice and that buying a diamond is one of the most significant purchases they will make. This is why we have produced this guide to introduce you to the most precious gem of all – the diamond.

When you are choosing a diamond there are the four C’s you need to consider:

Carat: Diamonds are not measured by size, but by weight. The unit is the carat, which is divided into 100 points – an example would be 50 points being described as half a carat. The carat weight determines most of the gem’s value.

Colour: Colour is perhaps the most important characteristic of a diamond and a key factor for determining its value. Ideally, colour should be totally absent (Type 1), except in the case of special fancy colours (Type 11). There is a precise scale of colour grades defined by the letters of the alphabet, with H being the most common commercial white colour. The grades are:

D-F is colourless
G-H is white
I-K is faint colour
L-M is yellow

Cut: The cut of a diamond has the greatest influence on its brilliance, liveliness or sparkle, causing light to “dance”. The most popular shape of a diamond is the round or “brilliant cut”, which has 58 precise facets. This is a fairly modern cut whereas another round diamond is the “old-cut” which is found mainly in antique and second-hand jewellery.
There are other cuts which would be called fancy shapes: they are emerald, oval, heart, princess, pear, marquis, Asscher, cushion and radiant cuts.

Clarity: The clarity of a diamond is assessed by examination of its imperfections, normally under a 10x magnification. Almost all diamonds contain traces of non-crystallised carbon called inclusions. These inclusions can be black, grey, white or look like “bubbles” and are nature’s way of fingerprinting diamonds making every stone unique. The fewer inclusions there are, the rarer, more desired, and expensive the diamond is.

The clarity grading is:

IF clean internally with minor surface blemishes
VVS1-VVS2 very, very small inclusions
VS1 – VS2 very small inclusions
SI1 – SI2 small inclusions
I1-I2-I3 inclusions visible to the naked eye (sometimes known as P1, P2 and P3, usually with many black markings).

A guide to the effect of clarity in a diamond is:

IF to VS2 will sparkle with intensity
SI1 to SI2 will just sparkle
I1 to I3 will lack sparkle and “life”

We are always pleased to advise you and help you investigate these four C’s and choose a setting - to match the right diamond with your budget.