The cut is the only one of the 4Cs to be influenced by man. The other "3Cs" namely the clarity, carat, and colour are determined by nature! The cut is what gives the diamond its brilliance and fire, and is an extremely important feature to consider when purchasing a diamond.

An ideal cut diamond is designed to get as much light reflected back through the top or "table" of the diamond to create fire, brilliance and scintillation. This can only be achieved if the diamond has been polished with specific angles on all of its 57 facets (in the case of a round brilliant diamond). If the diamond is too deep on the bottom then light will be lost through the sides making the stone appear a little dull and causing what is commonly known as the "fish eye" effect. If it is too shallow then it may appear dark.

You may, for example, come across two diamonds each weighing one carat. One will have a diameter of 6.50mm and the other 5.95mm. The latter will be much deeper, probably with a very thick girdle and an over sized crown to make up for the weight lost in the "spread". If this stone had perfect proportions it should only weigh 0.90carat, but then it will only have the worth of a 0.90carat diamond! Diamonds of specific weights will have specific ideal proportions. This is where Certification has proved to be a great help for the consumer when purchasing diamonds.