Understanding the 4Cs of a Diamond

A practical guide to cut, colour, clarity and carat weight, and why the grades should be considered together.

The 4Cs work together

Cut, colour, clarity and carat weight are useful because they give customers and jewellers a shared language. They should not be read as four separate scores where the highest number or letter automatically makes the most desirable stone.

A diamond with balanced proportions, pleasing brightness and a size that suits the design may be more attractive in person than a larger stone with weaker cut or less harmonious proportions.

Cut

Cut describes how well a diamond has been fashioned, including proportion, symmetry, polish and the way the facets return light. For many customers, cut has the strongest visible influence on brightness, fire and scintillation.

Cut grading is most standardised for round brilliant diamonds. Fancy shapes are assessed with more judgement, so photographs, videos and measurements can be especially useful.

Colour

Colour grades describe the presence or absence of body colour in a diamond. In colourless to near-colourless diamonds, differences can be subtle and are often influenced by the setting metal and stone shape.

Some customers prefer a bright white appearance, while others are comfortable choosing a warmer grade when the stone has appealing life and suits the jewellery design.

Clarity

Clarity describes internal features and surface characteristics. These features are common in natural diamonds and are part of how a stone formed.

A clarity grade does not tell the whole visual story. Location, size, colour and reflectivity of inclusions matter, as does whether they can be seen without magnification.

Carat weight

Carat is a measure of weight, not face-up size. Two diamonds of the same carat weight can look different in scale depending on their measurements and proportions.

Larger carat weight does not automatically mean a more attractive diamond. Balance, setting, hand scale and personal preference should all be considered.

Reports and valuations

A grading report records the characteristics assessed by a laboratory for a particular stone. It is not the same as a valuation and does not determine retail, insurance or resale value.

Report availability varies by product. Ask what documentation is available for the individual diamond you are considering.