The 4 C’s of Diamonds


4 factors determine the value of a diamond: cut, colour, clarity and carat. These are known as the “4 C’s of Diamonds”. Find out more about the 4 C’s in our short guide.


The most important of the four aspects of a diamond is it’s cut. This is because it has the biggest influence on the gemstone’s sparkle. The 3 elements that affect the gem’s appearance are:

  • Brilliance – light reflected from the diamond.
  • Fire – flashes of colour in the stone.
  • Scintillation – light or dark areas when the diamond is moved.

There is a scale to rate each cut of diamond, which ranges from excellent to very poor. The rating system is based on the amount of light reflected out of the stone. An “Excellent” cut diamond will reflect light beautifully, maximising all 3 factors. While a “Poor” cut diamond will lose a lot of light through the sides and bottom, which will give it a dull look.


A diamond’s value is also measured by it’s lack of colour. The gemstones often have a natural light, yellow hue. Completely colourless diamonds are very rare, thus they are more expensive.

The yellow is not very noticeable in “Near Colourless” diamonds. Especially not when in a yellow gold setting, as the gold brings out the white in the diamond.


The clarity of a diamond is the number of flaws that the gemstone has.

Imperfections occur in the natural process of making a diamond. It’s defects are what make each gem unique. However, they do interfere with how much light can pass through the stone. Thus, they affect the sparkle and beauty of it.

A scale measures how severe the blemishes are. A “Flawless” diamond has no inclusions, which is very rare. “Very Slightly Included” diamonds have a few minor flaws which aren’t visible to the naked eye. An “Included” diamond has many imperfections that are easy to see.


When discussing gold jewellery, the carat measures gold purity. But with diamonds, the carat is the weight of the stone, and not the size which is widely thought.

Carat is the least important of the 4 C’s of diamonds, as 2 stones of the same weight can vary in value significantly. This is based on the quality of the gemstones cut, colour and clarity.