A Guide
Cut, Colour, Clarity, and Carat: the foundation of diamond grading, plus the quieter considerations that separate good from exceptional.
The Foundation
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.
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.
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.
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.
Beyond the Report
Two often-overlooked grades that separate a beautiful diamond from a merely good one. We require Excellent on both.
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.
Provenance is non-negotiable. Every stone we offer comes with a fully traceable supply chain, whether natural or laboratory-grown.
Independent grading from an accredited laboratory, never in-house. The report travels with the stone.
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.
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 a fifth-generation eye, and it turns down most of what it is shown.
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.
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
An IGI or GIA report is five minutes of reading that most buyers never do. Here is the whole skill.
Asked, answered plainly
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.
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.
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.
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.
The List
The list is written to first: pieces, prices, and first keys to the doors.