Cut
How well the stone has been cut, meaning its proportions, symmetry and polish, not its shape. A well-cut diamond returns light back to your eye; a poorly cut one looks glassy or dark in the middle. Of the four Cs, cut makes the biggest difference to how a diamond looks, so it is the last place to save.
Colour
Most white diamonds have a trace of yellow. Colour is graded by letter, from D (no colour at all) onwards.
| Grade | What you see |
|---|---|
| D–F | Colourless. No trace of colour. |
| G–H | Near colourless. Very hard to tell from colourless once set. |
| I–K | Faint warmth, most visible in white metals and larger stones. |
In yellow or rose gold, a G–H or even I–K stone looks white against the warm metal, so you can save here.
Clarity
How many tiny marks, called inclusions, the stone has inside, and how visible they are.
| Grade | Meaning |
|---|---|
| FL / IF | Flawless or internally flawless. Rare. |
| VVS1–2 | Very, very slightly included. Marks are hard to find even under magnification. |
| VS1–2 | Very slightly included. Nothing visible to the eye. |
| SI1–2 | Slightly included. Usually clean to the eye, worth checking stone by stone. |
For most people, VS is the point where paying more buys nothing you can see. Step cuts such as emerald and Asscher show inclusions more clearly, so aim higher with those.
Carat
Carat is weight, not size: one carat is 0.2 grams. A one-carat round diamond is about 6.5 mm across. Prices rise faster than weight, so a stone just under a round number, such as 0.9 carats instead of 1.0, can cost noticeably less and look almost the same.
Certificates
A certificate from an independent laboratory such as GIA, IGI or HRD records a diamond’s grades, so you know exactly what you are buying. We recommend one for any centre stone.
Lab-grown diamonds
Lab-grown diamonds are real diamonds, the same material as mined stones, grown in months rather than formed over millions of years. They are graded the same way and cost considerably less. Whether you choose natural or lab-grown is a personal choice; you can set either in the Studio.