The 4C’s: Variables governing value of diamond

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The 4C’s are a common standard in the diamond and jewellery industry representing Cut, Colour, Clarity and Carat weight. They were introduced by De Beers over 50 years ago to help consumers understand the value of a diamond.


Cut is a term used twofold to either describe the shape of a diamond or the ideal proportions of a diamond. It is the only C influenced by hand as the other variables are governed by nature.


There are varying shapes of cut of diamond including round brilliant, princess, asscher, emerald, heart, pear, oval, marquise, radiant and cushion.

A diamond polisher’s challenge is to deliver from a rough diamond a polished diamond that offers maximum brilliance and fire reflected back to the viewer. To achieve this, a polisher has to adhere strictly to the ideal mathematical proportions of each shape which are applied to the three main components of a diamond, the crown, girdle and pavilion.

If a polisher adheres to the ideal proportions of a diamond shape an ideal cut grade will be issued and if there is deviation away from ideal proportions, a weaker cut grade will be issued from diamond grading laboratories.


Colour is a term used to describe the subtle difference between the colourless grade of D-F to the near colourless and off white diamonds which then appear to draw a very slight tinge of yellow which increases to a more noticeable yellow at the end of colour scale. Grading of colour is performed under controlled lighting usually with a master diamond colour set for comparison to help accuracy in determining colour.

Inclusions in a diamond may include cracks, fractures, carbon, clouds and natural growth lines. Diamond grading laboratories indicate the location of inclusions in a diamond which can vary from centre of the stone to the girdle.

Carat Weight

Carat is the measure of weight for diamonds and needs to be distinguished from the size of diamond, which is affected by cut and shape of the stone. There are 100 points to 1.00 carat which is equal to 1/5 of a gramme. If you hold colour and clarity constant and increase the carat weight of the diamond as per the illustration above, the price of the diamond increases dramatically.

The 5th C is often used to refer to the Jeweller! Another subject in itself!