> A diamond's value rests on four criteria, the 4Cs: Carat (weight), Colour, Clarity and Cut. Of the four, Cut governs the sparkle — a well-cut diamond retur

*Source : https://meilleures-bijouteries.fr/en/guides/diamond-4cs-guide/*

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● Guide

# The 4Cs of a diamond: carat, colour, clarity, cut

Published on **24/02/2026** · By **Sébastien Joumel**

In brief

**A diamond's value rests on four criteria, the 4Cs: Carat (weight), Colour, Clarity and Cut.** Of the four, **Cut** governs the sparkle — a well-cut diamond returns light, while a poorly proportioned one looks dull regardless of weight. Understanding the 4Cs lets you trade off intelligently instead of paying for a number.

## Carat: weight, not apparent size

**Carat** measures a diamond's weight: 1 carat = 0.20 gram. Price does not rise linearly — it jumps at round weights (0.50 ct, 1 ct), which are in high demand. A 0.90 ct stone often costs far less than a 1.00 ct one for a diameter difference that is nearly invisible. Buying just below the thresholds is a smart saving.

## Colour: from colourless to tinted

**Colour** is graded from **D** (perfectly colourless) to **Z** (noticeable yellow). D-E-F are colourless, G-H near colourless, I-J slightly tinted but often invisible once set. On a yellow- or rose-gold setting, a G-J colour looks great and costs less than a D. Colour is really only visible when comparing two stones side by side.

## Clarity: the inclusions

**Clarity** describes natural inclusions. The scale runs from **FL/IF** (loupe-clean) to **I** (visible to the eye). **VS1-VS2** and **VVS** grades are 'eye-clean': no need to pay for IF when a VS stone's inclusions stay invisible without a loupe. Just check the inclusions are not in the centre of the table.

## Cut: the C that makes it sparkle

**Cut** (not to be confused with shape) grades proportions, symmetry and polish, from **Excellent** to **Poor**. It is the only C fully controlled by people, and the most important for sparkle: an 'Excellent cut' diamond returns light through the top (the 'fire'), while a poor cut lets light leak out of the sides. **Always prioritise Cut**; you can compromise on the other three, not on this one.

## Frequently asked questions

Which C matters most?

Cut. It determines the diamond's sparkle and fire. A well-cut stone with average colour or clarity will look better than a paper-perfect but poorly proportioned one.

Which combination offers the best value?

A common sweet spot: Excellent cut, G-H colour, VS1-VS2 clarity, and a weight just below a round threshold (0.90 ct rather than 1.00 ct). You get a bright, eye-white stone without paying the premiums of extreme grades.

Do I need a GIA certificate?

For a significant diamond, yes: an independent lab certificate (GIA, HRD, IGI) attests the 4Cs and protects your purchase. Without one, you only have the seller's word on the stated characteristics.

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