Robert Glenn

The 4cs of Diamond Quality

You’ve probably heard of the 4cs of Diamond Quality, if you haven’t a Google search will certainly throw up a lot of results! 

The 4cs is a universal standard for grading diamonds. It’s a system based on colour, clarity, cut and carat weight – the 4cs!

Colour sounds simple but there are 23 different types of diamond colour (in the GIA system used here), from D (colourless) to Z (light). Generally the more white the diamond the more valuable it is, but this only grades white diamonds. Other diamonds, like pink and yellow, fall outside this system and are referred to as ‘fancy-coloured’ diamonds. This type of diamond is harder to value.

Clarity is all about the blemishes within the stone – you’ve got to remember diamonds spend a long time under an awful lot of pressure! With this in mind Flawless diamonds are the most valuable. There are a 11 further stages of clarity. Flawless, Internally Flawless, VVS1 (very very slightly included), VVS2, VS1 (very slightly included), VS2, SI1 (Slightly included), SI2, I1(Included), I2 and I3. To ascertain clarity the stone is examined at 10x magnification – most flaws are barely visible to the naked eye.

Cut is the human element of the value. Diamond cutters are highly skilled craftspeople who look at a diamond and select the right cut to maximise its ‘return of light’. There are five grades for diamond cutting: Excellent; Very Good; Good; Fair; Poor. The cut is the hardest of the 4cs to evaluate and often has the biggest effect on diamond value.

Carat is a guide to size. Each ‘carat’ is sub-divided down into a hundred points allowing for very precise carat weights for every size of diamond. Where more than one diamond is used carat weights are added together to give an overall carat weight for the piece. 

At Robert Glenn we pride ourselves on our diamond selection. We always take time and care to select the very best for our clients, and source our diamonds to suit every taste and budget.

< Back