The 4Cs of Diamonds

In order to select the diamond that’s right for you, it is important to consider what is known as the 4Cs of diamond quality – Colour, Clarity, Cut and Carat Weight. The 4Cs were developed by the Gemological Institute of America (GIA) and are used by jewellers and gemmologists worldwide as a way of describing and comparing diamond characteristics.


The colour of a diamond in fact refers to the lack thereof. The degree of colour in a diamond is measured using the GIA colour-grading system which ranges from D (colourless) through to Z (light colour). The less colour a diamond has, the higher its value.

GIA Colour Scale

GIA Colour Scale

Image source: Gemological Institute of America Inc.

NOTE: The D-to-Z scale is used for grading white diamonds only, as fancy coloured diamonds (pinks, yellows, etc) are graded using their own respective colour scales.


Quite often, diamond shape is confused with cut. Shape refers to the outline of the stone whereas Cut refers to the arrangement of a stone’s facets and how they interact with light to give visual brilliance. For this reason, Cut is considered the most important characteristic of a diamond.

Standard round brilliant diamonds within the D-to-Z colour range are separated into 5 different cut grades as per the GIA Diamond Cut Scale.

GIA Cut Scale

Image source: Gemological Institute of America Inc.

The three main visual effects displayed by an excellent cut diamond are brightness (white light reflected from the diamond), fire (the rainbow effect present across the facets) and scintillation (the pattern of light and dark areas which gives the diamond its ‘sparkle’).


Clarity refers to the number of natural imperfections present in the diamond – ‘inclusions’ (internal) and ‘blemishes’ (external). Many inclusions and blemishes are only visible under 10x magnification and cannot be seen with an untrained, naked eye. Diamonds with little to no imperfections are the most valuable as they are extremely rare.

The GIA Diamond Clarity Scale contains a total of 11 grades which are separated into 6 main categories:

 GIA Clarity Scale

Image source: Gemological Institute of America Inc. 

  • Flawless (FL) - No imperfections are visible under 10× magnification. Extremely rare.
  • Internally Flawless (IF) - No inclusions (internal imperfections) visible under 10× magnification.
  • Very, Very Slightly Included (VVS1 and VVS2) - Very minor imperfections are extremely difficult to see under 10× magnification.
  • Very Slightly Included (VS1 and VS2) - Imperfections can be challenging to see under 10x magnification.
  • Slightly Included (SI1 and SI2) – Imperfections are visible under 10x magnification.
  • Included (I1, I2, and I3) – Imperfections are obvious under 10x magnification and often, to the naked eye.

 GIA Clarity

Image source: Gemological Institute of America Inc.   

Carat Weight

‘Carat’ refers to the weight of the diamond, not the size. One carat equals 200 milligrams. For precision, each carat is comprised of 100 points - for instance, there are 50 points in a half-carat diamond. On some occasions, you may hear a diamond’s weight verbally expressed solely in points (eg ‘a fifty pointer’).

As larger diamonds are harder to come by, the price of a diamond increases as the carat weight increases. However, it is important to note that carat weight alone does not determine price as colour, clarity and cut are also important determining factors.

Diamond Carat Weight Scale

Image source: Gemological Institute of America Inc.