What are the 4 C's?
The quality of diamonds is translated in the 4 C's:
- Carat (weight)
- Clarity (purity)
- Cut (quality of the cut)
These characteristics give an idea of the quality of a diamond and are used to identify stones.
The weight and size of a stone is expressed in carat. 1 carat is 0.2 gram and divided into 100 points (or 200 milligram). This scale is very precise in determining a stone's weight and is rounded up to two decimals.
Most diamonds used in jewellery have shades from white to yellow.
The colour of a white diamond stone is determined by an internationally recognized colour pallet. Colours range from D, colourless and the most searched for, to Z, the yellowest.
Diamonds can also be brown, orange, pink or blue. The most intense colour shades are called 'fancy' and this is mentioned on their certificate. These coloured diamonds are extremely rare and therefore very precious.
In order to determine the clarity (or purity) of a stone, an expert will look at it under a magnifying glass (x10 enlargement). Most diamonds are born with birth marks, known as inclusions. The fewer flaws are present, the more light can shine through the diamond, and the better it will sparkle. The diamond can shine more than any other gemstone if its clarity is of good enough quality.
The clarity of the diamond can be flawed in two ways:
- External impurities: the blemishes occur during the cutting process or are due to wear
- Internal impurities: these inclusions relate to any flaws within the stone. Many types exist.
Most common inclusions are:
- Black or dark spots, which originate in the coal.
- Clouds - microscopic veils which weaken the clarity
- Feathers - most impurities in diamonds come out of the molecular break during the creation process of a stone from coal
Determining the clarity grades
Most often, a loupe or microscope (x10 enlargement) are used to determine the clarity of a stone. This means that flaws that cannot be seen at this enlargement are considered as non-existing.
Cut is a diamond's most important characteristic. It is the factor that fuels a diamond’s fire, sparkle and brilliance. Cut refers to a diamond’s proportions, symmetry and polish. If the depth of the diamond is too shallow or too deep it will allow light to escape through the sides or the bottom of the stone. A well-cut diamond will direct almost all the light through the crown.
The term 'cut' can also describe the shape of a diamond. Shapes other than the standard round brilliant cut are called fancy cuts. The most known are the marquise, pear, oval, heart and emerald cut.