Cut is the only one of the 4Cs entirely shaped by human hands, and the one that most directly determines a diamond's visible beauty. A poorly cut diamond stays dull, even with excellent colour and clarity.
"Cut" actually sums up three distinct assessments: proportions (the stone's overall geometry), polish (the finish of each facet), and symmetry (the precise alignment of facets with each other). All three must be excellent for a diamond to reach its full brilliance potential.
| Cut grade | Excellent | Very Good | Good | Fair |
|---|---|---|---|---|
| Description | Maximum refraction · perfect brilliance | Very high brilliance · intense fire | Standard quality proportions | Imperfect cut |
GIA assigns an overall cut grade (Excellent to Fair) only to round brilliant diamonds. For fancy shapes, pear, oval, marquise, cushion, emerald, the report lists polish and symmetry separately, with no combined score. This is why a dealer's eye and experience matter more for these shapes: two stones with the same figures on paper can have very different sparkle in hand.
A GIA or HRD report gives you numbers, but nothing replaces direct examination under a loupe. It's the step I spend the most time on before offering a stone. Cut is, of all criteria, the one that's most immediately visible, and the one an unwary buyer is most likely to underestimate.
Discover diamond shapes →Excellent, across all three parameters (proportions, polish, symmetry). It's the criterion that most influences brilliance, more than colour or clarity on a round brilliant.
Shape is the stone's outline (round, oval, pear, emerald...). Cut is the quality of the craftsmanship: the proportions, polish and symmetry that determine sparkle, whatever the shape.
GIA reserves the combined grade (Excellent to Fair) for round diamonds, where ideal proportions are well established scientifically. For fancy shapes, no equally precise standard exists yet, which is why direct examination matters so much.
Often yes, for anyone looking for a good budget compromise: the brilliance difference between Very Good and Excellent stays subtle to an untrained eye, unlike the gap with Good or Fair, which is more noticeable.
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