What you need to know about the 4c's

The Selene asymmetrical oval diamond cluster engagement ring on a white background

The 4 C's are a universal grading system for diamonds, in place to keep consistency within the diamond industry. Developed by the Gemmological Institute of America (GIA), diamonds purchased from jewellers often come with a GIA certificate describing the stone in terms of the 4 C's.

Colour

The less colour, the higher the value.

This refers to colourless diamonds, not to fancy-coloured diamonds (pinks and blues) which lie outside of this scale. The scale refers to the body colour of the diamond, which may be completely lacking in colour (the ideal) or may feature hints of yellow or brown. The scale runs from D to Z, with D being completely colourless and Z exhibiting light colour. Even though the colour difference may be subtle, it has a profound impact on the value of the stone.

GIA diamond colour scale chart

Model wearing the Flutterby all-diamond ring in rose gold — handmade contemporary jewellery London

Clarity

Natural imperfections.

Diamonds are formed within the mantle of the earth and pushed to the surface during volcanic eruptions. A diamond completely free from inclusions or blemishes is quite rare, and the clarity grade refers to the size, nature and location of these imperfections.

  • FL – IF (Flawless – Internally Flawless): No inclusions visible using a 10x lens. Very rare.
  • VVS1 – VVS2 (Very Very Slight Inclusions): Difficult to see inclusions with 10x lens. Excellent quality.
  • VS1 – VS2 (Very Slight Inclusions): Difficult to see inclusions with 10x lens.
  • SI1 – SI2 (Slight Inclusions): Easy to find with 10x lens but difficult to see with the naked eye.
  • I1 – I3 (Inclusions): May be seen by the naked eye.
GIA clarity diamond scale chart

Carat

1 carat = 0.2 grams.

Carat is the unit of weight used for diamonds. It is not necessarily representative of size — a small difference in carat weight can greatly affect the price of the diamond.

Profile view of the Amoret marquise diamond solitaire ring showing the elegant, low-profile claw setting and the slender handcrafted band.

Cut

The cut of a diamond has been mathematically predetermined.

Diamonds have a complex relationship with light. Cut too shallow and the light falls straight through; cut too deep and the light struggles to reflect back to the eye, generally moving out of the side of the stone. Diamonds have optimum angles at which they must be cut to produce maximum brilliance and dispersion — this is what gives them their sparkle.

Cut grades are classified as: Excellent – Very Good – Good – Fair – Poor

At Nude Jewellery we can source a variety of diamonds for your bespoke commission. For information on bespoke diamond pieces or for general advice, please get in touch with our London studio.