Diamond Boutique

Diamond Grading - The most important of the 4 "C"s

Most people who have purchased or researched diamonds would have discovered what we in the industry call the 4 C’s. It seems that most people understand 3 out of the 4 C’s (Colour, Clarity and Carat), however the 4th C – Cut – is often over-looked.


Idealy a diamond should have no colour. Increasing degrees of colour are measured on a scale starting at D (colourless) to Z (deeply coloured). Diamond Boutique's minium standard for colour is 'H'.

Diamond Colour Chart

Source: Ygraph


The clarity of a Diamond is determined by the presence of internal 'inclusions' or external 'blemishes'. Clarity is ranked on a scale from F to P3, where 'F' is Flawless, and 'P3' is heavily included. This rank is calculated based on how many inclusions there are, how big they are, what their colouring is and where they are located in the stone. Some may be visable with the naked eye (which would result in a low grade such as P1, P2 or P3), and others would need a loop, or microscope to see. Diamond Boutique's minimum standard for clarity is SI2.

Diamond Grading Chart

Source: Ygraph


Carat refers to the size or carat weight of a gemstone. Carat weights of less than 1 are generally referred to as 'points'. Half a carat (0.50ct) would generally be referred to as 50 points. There is also an important difference between the carat weight of a single stone and the total carat weight of a ring. For example a ring with 10 diamonds, each with a carat weight of 5 points would be advertised as 'half a carat of diamonds' by many chain jewellery stores.


'Cut' is the often forgotten “C”, and is one of the more important factors (along with colour) of what makes a brilliant diamond. We will give a more in depth focus to 'cut' or 'make' as it is more important than many people realise. Purchasing a stone that is of a poor make means that no matter how high the colour and clarity of the diamond is, the stone will not have good light return and can look lifeless.

In layman’s terms there is a specific science to diamond cutting. A diamond's beauty can be affected by the skill of the cutter in achieving the correct combination of crown angles and depth percentages. In a well cut diamond a ray of light that enters the table of a diamond will reflect on the internal mirrors to return all of that light back out of the table and to the viewer. This is a scientific principle known as 'total internal reflection'. The cut of a diamond has three attributes:

  • Brilliance (or light reflection)
  • Fire (or dispersion of light into the colours of the spectrum) and
  • Scintillation (or sparkle).

If a diamond is cut too deep or shallow, the light that enters the table will not be returned through the side it entered, but lost through the bottom or another side.

Diamond Cut

Source: Ygraph

There is a reason for the 58 facets in a round brilliant cut diamond. The proportions and relationships between the table size, crown angle and pavilion depth are extremely important. The allure of a diamond depends more on this than anything else.

So how do you know if a stone is well cut? To grade how well a diamond is cut there are further sub categories they are Symmetry, Pollish and cut (or proportion).This is what people in the industry are talking about when they mention triple x (or excellent, excellent , excellent) A diamond with a triple x grade for cut will display the hearts and arrows effect.

On most certificates that accompany a diamond there is a diagram of the side view of a diamond with many percentages and angles on it. All of these measurements together will indicate how well your diamond is cut. The diamond will then be graded in accordance with these measurements.

At Diamond boutique we pride ourselves in our knowledge and with a diamond grader on staff we are able to interperate any diamond certificate that may come from any one of the numerous gemological laboratories worldwide. When purchasing a diamond through Diamond Boutique we will talk you through all aspects of your diamond and its certificate so that you have a true understanding of the quality of gemstone you are receiving.