What Are the 4Cs of a Diamond?

Cut, Colour, Clarity and Carat Explained

Two diamonds in the same display case. Same shape, similar size. One costs significantly more than the other and the salesperson hasn't explained why yet.

The 4Cs are cut, colour, clarity, and carat, the four criteria every diamond in the world is graded against. GIA standardised the system in the 1950s. Before that, quality descriptions varied by seller and buyers had no reliable way to compare stones across different retailers or markets.

Knowing the 4Cs going in changes the conversation. You understand what you're being shown, you know which questions to ask, and you can compare two stones on something more concrete than gut feel.

→ For a broader overview before you start: The Complete Guide to Diamonds

Cut

Cut is the most important of the four Cs and the one most commonly confused with shape.

Shape is what a diamond looks like from above. Round, oval, pear, emerald, those are shapes. Cut is about proportion, symmetry, and the quality of faceting. A round diamond can be cut to an Excellent standard or a Poor one. The shape doesn't tell you that.

What cut controls is light. When a diamond is cut to the right proportions, light enters through the top, bounces off the internal facets, and comes back out through the top. That return of white light is brilliance. Fire is the splitting of that light into colour. Scintillation is the flash you see when the stone or the light source moves. All three depend on cut quality.

A poorly cut stone lets light leak out the sides or bottom. It looks flat, sometimes glassy, even with strong colour and clarity grades. A high clarity grade on a badly cut diamond is genuinely wasted.

GIA grades cut across five levels: Excellent, Very Good, Good, Fair, and Poor. For round brilliants, Excellent or Very Good is the minimum worth considering. Below Good, the difference shows in normal light. Fancy shapes, oval, cushion, and pear don't have a standardised cut grade, so look at symmetry and length-to-width ratio instead.

If the budget gets tight, cut is the last place to compromise.

Colour

Diamonds are graded on a colour scale from D to Z. D is colourless. Move toward Z and a yellow or brown tint becomes progressively more visible. The grading is done face-down, compared against master stones under controlled lighting, not how you'd view a ring in a shop window, which is worth keeping in mind.

The ranges that matter in practice: D to F is colourless and carries a premium for a difference that's nearly impossible to see once the stone is set. G to I is near colourless, this is where most buyers land, and for good reason. It faces up white in almost any setting and costs noticeably less. J and K have a faint warmth that yellow gold tends to absorb well, but white gold and platinum make more obvious. Below that, the tint is visible and generally avoided in fine jewellery.

Setting metal has a real effect on how colour reads. Yellow gold masks slight warmth in a stone you can go lower on the scale without anyone noticing. White gold and platinum create contrast, so colour shows more clearly against them. If the setting is white metal, G or above is the safer range.

Carat weight changes things, too. A faint tint in a small stone is almost invisible. In a 2ct stone, the same grade reads differently. The larger the diamond, the more the colour grade matters.

G or H hits the right balance for most buyers, faces up white, no visible tint, and the price difference from D is real.

Clarity

Clarity measures inclusions' internal characteristics that form as the diamond grows, and surface blemishes. Most are microscopic. What matters is whether any are visible to the naked eye.

The scale goes FL to I3. FL and IF are flawless. VVS1 and VVS2 are nearly invisible even under a loupe. VS1 and VS2 show under magnification but not to the naked eye. SI1 is usually eye-clean; SI2 needs stone-by-stone inspection. I1 to I3 are visible without any magnification.

The standard that actually matters is eye-clean no inclusions visible at normal viewing distance. A VS2 and an SI1 can both pass. The grade tells you what's there under magnification, not what you'll see wearing it.

Where inclusions sit matters too. One under the centre table facet is more visible than one near the edge. The grading certificate shows a placement diagram worth a look before you decide.

VS1 or VS2 for certainty. SI1 for value, but inspect the specific stone.

Carat

Carat is weight, not size. One carat equals 0.2 grams precise, but it doesn't tell you how large a diamond looks face-up.

Cut has more effect on apparent size than most buyers expect. A well-cut 0.90ct can look bigger than a poorly cut 1.00ct. Oval and marquise shapes also face up larger than round at the same weight because of how they spread across the finger.

Price jumps at round numbers 0.50, 1.00, 1.50, 2.00ct. A 0.98ct and a 1.00ct are visually the same stone. The premium at the threshold is real and avoidable.

For multi-stone pieces, pavé rings, earrings, bangles check whether the listed carat weight is the centre stone or total carat weight (TCW). They're not the same number.

How the 4Cs Work Together

They interact. A strong clarity grade on a poorly cut stone is wasted. A high carat weight with weak cut looks smaller than it should.

For most buyers the order holds: cut first, eye-clean clarity, G–I colour, then carat. Cut is the one C that affects everything else; it's the last place to compromise.

Before You Buy

The 4Cs exist so buyers and sellers are speaking the same language. Knowing them going in means you can compare stones on facts rather than feel.

At Dorrado in the Dubai Gold Souk, every diamond comes certified. Book a WhatsApp appointment before you visit if you'd prefer to come in with a clear brief.

→ The Complete Guide to Diamonds