Diamond Guide

Many people have heard of “the four C's” but what do they refer to?

  • Carat
  • Clarity
  • Colour
  • Cut


This refers to the weight of the stone. Today One carat is dived into 100 points so 50 points would equal ½ a carat. As larger stones are harder to find they are also more expensive by carat weight, so a three carat stone would be far more expensive than 2x 1½ carat stones. One carat=200mg or a fifth of a gram. The term carat is a translation from the Greek Keration meaning carob seed and was used for thousands of years to mean 1 carat=1 carob seed.


The GIA Clarity Scale contains 11 grades. In determining a clarity grade, the GIA considers the size, nature, position, colour and quantity of internal characteristics of the stone visible under 10× magnification.

  • Flawless (FL) - No inclusions or blemishes are visible to a skilled grader using 10× magnification
  • Internally Flawless (IF) - No inclusions and only blemishes are visible to a skilled grader using 10× magnification
  • Very, Very Slightly Included (VVS1 and VVS2) - Inclusions are difficult for a skilled grader to see under 10× magnification
  • Very Slightly Included (VS1 and VS2) - Inclusions are clearly visible under 10× magnification but can be characterized as minor
  • Slightly Included (SI1 and SI2) - Inclusions are noticeable to a skilled grader using 10× magnification
  • Included (I1, I2, and I3) - Inclusions are obvious under 10× magnification and may affect transparency and brilliance


Diamonds  are graded using the GIA’s colour-grading scale for diamonds from colourless to near-colourless, with slight hints of yellow or brown. Colour is graded from D (the best, perfect white) down to Z (severely discoloured).Each grade has a  defined range of colour appearance. Diamonds are colour-graded by comparing them to stones of known colour under precise viewing conditions and controlled lighting.

In colourless Diamonds, colours D-F command a higher price than those with a yellowish tint due to their rarity.


This has a large influence on the overall look of the diamond as a stone that is too deep or too shallow will not reflect the light back through the table of the diamond resulting in a stone with very little brilliance. This is the only one of the four C's that is influenced by the cutter

The cut of the Diamond is purely a way of telling how well the light will reflect and should not be confused with the shape of the stone.

Richard Cowell
01626 772736
07950 221651