The 4Cs, explained without the jargon
Updated 16 October 2026
The 4Cs are cut, colour, clarity and carat weight. They are how every diamond is graded, laboratory-grown or earth-mined, and they are printed on the grading report that comes with your stone. Here is what each one means and how much it matters to what you will actually see.
Cut
Cut grades how well the diamond has been proportioned and polished, which controls how it returns light. It is the grade that most affects sparkle, so it is the one we never compromise on. For round brilliants we only use stones graded Excellent (or Ideal, depending on the laboratory). Fancy shapes such as ovals and pears do not receive a single cut grade, so we select them by proportions and by eye.
Colour
Colour runs from D (colourless) down the alphabet to Z (light yellow or brown). The differences between neighbouring grades are very slight. Most people cannot see a difference between D and G once the stone is set, especially in white gold or platinum. In yellow gold, a G to H stone looks the same as a D. We grade our standard selection D to G.
Clarity
Clarity describes tiny internal features (inclusions) and surface marks (blemishes). The scale runs from Flawless through VVS and VS down to SI and I. A VS2 diamond has inclusions that are hard to find even under 10x magnification, and invisible to the eye. That is why VS2 is our minimum: paying for higher clarity buys something you cannot see. Step cuts such as the emerald cut show inclusions more readily, so we use VS1 or better for those.
Carat
Carat is weight, not size. One carat is 0.2 grams. Two diamonds of the same weight can look different sizes depending on their shape and how they are cut: an oval or a pear spreads its weight across a longer outline and looks larger from above than a round of the same weight.
Prices also jump at round numbers. A 0.95 ct stone can cost noticeably less than a 1.00 ct stone that looks identical. If you are flexible, ask us to look just under the round number.
Where to spend
- Cut first, always.
- Carat next, if size matters to you.
- Colour and clarity only to the point where differences stop being visible: around G and VS2.