A Guide

The 4 C's, and beyond.

Cut, Colour, Clarity, and Carat: the foundation of diamond grading, plus the quieter considerations that separate good from exceptional.

The Foundation

The Four C's

Move along each scale to read what the grade actually means, and where this house buys.

Cut

Cut is the single greatest influence on a diamond's brilliance. It governs how light travels through the stone, returning as fire, scintillation, and life. We favour stones graded Excellent or Ideal, prioritizing beauty over yield.

What the house looks for: light returned evenly across the whole crown, no dark heart, no fish-eye. The grade opens the door. The pattern decides.

The cut grade, Excellent to Poor

Excellent

Proportions that return light across the whole crown. On a round brilliant this is the grade that decides how the stone looks, and it is the one we start from.

Marked: where we buy. Excellent or Ideal, and then the pattern is read by eye.

Colour

Graded D (colourless) through Z (light yellow), colour is most apparent in larger stones and certain settings. We typically curate within D to G, where the stone reads as bright white to the unaided eye.

What the house looks for: the stone face up in daylight, beside its neighbours. A G that faces up white beats a D that was bought for the letter.

The white scale, D to Z

Colourless

D, E and F. Colourless. Ice-white on paper and in hand, and priced for the letter as much as for the look.

Marked: where we curate. D to G, which is all of colourless and the top of near colourless.

Clarity

Clarity describes the natural inclusions formed deep within the earth. From Flawless to Included, we select eye-clean stones (no inclusions visible without magnification) to balance beauty and value.

What the house looks for: where the inclusion sits, not just what grade it earned. A feather hidden under a prong is invisible for life. The same feather under the table is a permanent guest.

The clarity scale, Flawless to Included

Inclusions a jeweller finds under a loupe, not the eye. The quiet sweet spot.

Marked: where eye-clean stones are found. Grade opens the range. Where the inclusion sits closes it.

Carat

Carat is weight, not size. A well-cut 1.00 ct stone can appear larger than a poorly cut 1.20 ct. We treat carat as one input among many, never the headline.

What the house looks for: spread. The millimetres the eye actually sees, against the weight the invoice actually charges. We refuse stones that bury their carat in depth.

Weight brackets, and what the eye sees

1.0

One carat and up. The first of the round numbers, and the first place the price jumps for the number rather than for the stone. A 0.96 faces up almost identically and costs noticeably less.

No band is marked here. We treat carat as one input among many, and we read spread in millimetres before we read weight.

Beyond the Report

What truly matters

Four things the certificate measures, and four it never will.

On the certificate

Polish & Symmetry

Two often-overlooked grades that separate a beautiful diamond from a merely good one. We require Excellent on both.

Fluorescence

A natural reaction to UV light. In moderation it can brighten a stone; in excess it can dull. We disclose it transparently for every diamond.

Origin & Ethics

Every stone carries its independent report; origin is stated where the laboratory records it.

Certification

Independent grading from an accredited laboratory, never in-house. The report travels with the stone.

Never on the certificate

Make

Make is the trade's word for how well a stone was fashioned: proportions, polish, and symmetry taken as one. Two diamonds can share a grade and differ in make. The better make holds its light; the lesser one leaks it. We buy on make first.

The Trained Eye

A report records what was measured. It does not record whether the stone is beautiful. That judgement is made by eye, in daylight, against other stones. Ours is the eye of a family in the diamond trade for generations, and it turns down most of what it is shown.

Light Performance

Beyond the cut grade lies how a stone actually behaves: brightness, fire, and the on-off flash the trade calls scintillation. Two Excellent cuts can perform differently because proportions interact. We judge performance moving, in daylight, the way the stone will live.

Matched by Eye

Two identical certificates are routinely two different stones. Paper grades the parts; it cannot see the whole. When we build a pair of studs or line a riviera, the stones are matched by eye, against each other, and a pair that will not agree is rejected whatever its reports say.

The Paper

How to read a report

An IGI or GIA report is five minutes of reading that most buyers never do. Here is the whole skill.

The number
Every IGI or GIA report has a unique number. Verify it on the laboratory's own site before you pay, with us or with anyone. An honest seller will wait while you do.
The grades
Cut, colour, clarity, carat, plus polish, symmetry and fluorescence. These are the measured facts. They are the floor of the decision, not the ceiling.
The plot
The clarity plot maps each inclusion. Read where they sit: edges and prong positions disappear into a setting, the centre of the table does not.
The proportions
Table, depth, angles. Extremes in either direction usually mean weight kept at beauty's expense. Mid-range proportions age best.
The origin line
On a lab-grown stone the report states it plainly. Natural and lab-grown are graded on the same scales by the same laboratories; the origin line is the difference on paper.

Asked, answered plainly

Which of the 4 C's matters most?

Cut. It is the only C that people made, and it governs how the stone handles light. A well-cut stone a grade down in colour and clarity beats a poorly cut stone with a better certificate, at a lower price.

What does eye-clean mean?

No inclusions visible to the unaided eye at normal viewing distance. It is where clarity spending stops making visual sense: grades above eye-clean are purity you can only see with a loupe.

Why do two diamonds with identical certificates look different?

Because a certificate grades parts, not the whole. Proportions interact, inclusions sit in different places, and light behaves accordingly. This is why we match stones by eye, never by paper alone.

Are natural and lab-grown diamonds graded the same way?

Yes, on the same scales by the same independent laboratories, and the report states the origin. Grading tells you the stone's quality; it does not decide the natural-or-lab question for you.

Natural or lab-grown, honestly From the Cutting Floor Watch the Journey

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