What the four Cs are
Every diamond, lab-grown or mined, is graded on the same four qualities. Together they describe how a stone looks and what it costs. None works alone. A diamond is the sum of all four.Here they are in one line each, before we take them one at a time.
01Cut
How well the facets are arranged to return light. The single biggest driver of sparkle.02Colour
How colourless the stone is, graded from D through Z. Closer to D reads whiter.03Clarity
How few natural marks it carries, inside and out. Most are invisible without a loupe.04Carat
The weight of the stone, not directly its size. Price climbs steeply with it.Cut: the one that matters most
If you take one thing from this page, take this: cut does more for a diamond's beauty than any other C. It is the precision of the facets, the angles and proportions that decide how much light the stone gathers and throws back.A brilliant cut on a modest stone will outshine a lazy cut on a bigger, whiter one. Because of that, we never drop below Very Good, and on a round we hold Excellent.
Light returned by cut grade · relative
Excellent
Very Good
Good
Fair
Poor
Colour
Colour measures how close a white diamond comes to no colour at all. The scale runs from D (utterly colourless) down to Z, where a warm tint becomes visible. The catch: neighbouring grades are near-impossible to tell apart by eye.For most people, the sweet spot is G to H: it reads white on the hand, at a fraction of the price of a D. Warm metals such as yellow and rose gold hide warmth even further, so you can go a grade or two lower with them.
The D-Z colour scale
D
E
F
G · H
I · J
K-M
N-Z
ColourlessNear-colourless · best valueFaint warmth
Clarity
Every diamond forms with tiny natural marks: inclusions inside, blemishes on the surface. Clarity grades how few there are, and how easily they are seen, from Flawless down to Included.The word to remember is eye-clean: no marks visible to the naked eye at arm's length. Most stones in the VS to SI range are eye-clean, and paying for perfection only visible under magnification is money left on the finger.
The clarity scale
FL · IF
FlawlessVVS1-2
Very, very slightVS1 · VS2 · SI1
Eye-clean · best valueSI2
Slightly includedI1-3
Visible marksOne thing to watchClarity depends on where the marks sit. An SI stone with an inclusion tucked under a prong can look flawless face-up; a higher grade with a mark dead centre may not. Judge the individual stone, not just the letter on the certificate. Every stone in our library is viewable in full detail before you choose.
Carat
Carat is weight, not size: one carat is a fifth of a gram. Two stones of the same carat can look different in face-up size depending on shape and cut, which is why we offer every setting in exactly three weights: 1ct, 2ct and 3ct.Price climbs faster than weight, and it jumps at the round numbers everyone asks for. Stepping just under a round number saves meaningfully for a difference no eye can catch.
Relative face-up size · round brilliantIndicative outlines. Oval and emerald read larger than round at the same carat.
1ct
2ct
3ct
Where to spend
You almost never max out all four. The art is in the balance: protect what the eye actually sees, and ease off where the difference lives only on paper. Our house order, for a stone that looks its best on the hand:
1
Cut
Hold it high, Excellent or Very Good. It is what makes a diamond sparkle, and it cannot be recovered later.2
Carat
Set the size that feels right, then buy just shy of the round number to stretch the budget.3
Colour
Land in G-H for white metals; go a touch lower with yellow or rose gold.4
Clarity
Go as low as eye-clean, usually VS to SI, and no further. Perfection you cannot see is not worth paying for.Still weighing it up?Tell us your budget and we will suggest a balance of the four Cs that looks its best on your hand. No jargon, no pressure.
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