Diamond Three-Stone Engagement Ring

The 4 Cs

What are the 4 Cs and how do you assess the quality of a diamond? In the early 1940s, Robert M. Shipley, jewellery retailer and founder of The Gemological Institute of America (GIA), devised a set of standards by which any diamond, anywhere in the world, could be graded. These standards are known as the 4 Cs: Colour, Clarity, Cut and Carat Weight, and they are a universally accepted method for judging the quality of a diamond.


Cut refers to the proportions and facets of a diamond, not the shape, such as cushion, pear or round. The GIA refers to diamond cut on a scale ranging from excellent, very good, good, fair through to poor. The cut of a diamond is probably the most important aspect to look for when choosing a diamond, as even a flawless diamond cut poorly will not sparkle and flash as you would wish.

White diamonds are graded in colour on a scale from D to Z. Fancy coloured diamonds have their own colour scale.

White diamonds range from D to F Colourless, G to J Near Colourless, K to M Faint, N to R Very Light, S to Z Light.

Virtually all diamonds contain imperfections and inclusions. The GIA uses an 11 point grading scale. The term 'eye-clean' refers to diamonds that have inclusions that are not noticeable to the naked eye.
FL = Flawless
IF = Internally flawless
VVS1 - VVS2 = Very very slightly included
VS1 - VS2 = Very slightly included
SI1 - SI2 = Slightly included
I1, I2, I3 = Included

Carat Weight
A carat equals 0.2 grams and refers to the weight of the diamond. This is not to be confused with the word karat which identifies the purity of gold, such as 14 or 18 karat.

The 4 Cs are a guide to refer to when assessing a diamond's quality and price, however, you will probably find you are drawn to a particular piece of jewellery and in the end you won't worry too much about inclusions or colour grading. Be guided by your own eyes and you will love the diamond that speaks to you and feels truly special when you wear it.

Back to blog