Lab Grown Diamonds
Cushion or Radiant: Rounded Corners or Cropped Ones
Two soft-square shapes confused constantly β and one of them is far less predictable than the other.
Written by the Mapple Gems workshop, Surat Β· Updated 8 October 2026
Short answer
A cushion has rounded corners and softly curved sides; a radiant has straight sides and cropped corners, giving a crisper outline. The important practical difference is consistency: βcushionβ covers two completely different faceting styles β crushed ice and chunky β that look and behave nothing alike, while a radiant is far more predictable. So on a cushion you must ask which kind; on a radiant you mostly need to check the ratio.
These two get confused in listings and in shortlists, partly because a chunky cushion and a radiant can look similar in a thumbnail. On the hand they are not similar at all.
βCushionβ is the least standardised word in the shape vocabulary β it describes an outline and says nothing at all about the faceting, which is what you actually see. Two stones can both be sold as cushions, both weigh a carat, both carry identical grades, and look almost nothing alike. A crushed-ice cushion has many small facets producing a scattered, glittering, almost fragmented return. A chunky or antique cushion has fewer, larger facets giving broad, slow, distinct flashes. Neither is better; they are different stones with the same name, and no report distinguishes them β there is no field for it, no vocabulary for it, and no cut grade on any fancy shape to hint at it. A radiant, by contrast, is a much more consistent thing: straight sides, cropped corners, and a recognisable brilliant faceting pattern from stone to stone. So the two shapes need different questions. For a radiant, derive the ratio and watch the video. For a cushion, the first question is not the ratio at all β it is βcrushed ice or chunky?β, and a seller who cannot answer it has not looked at the stone.
Side by side
| Cushion | Radiant | |
|---|---|---|
| Corners | Rounded | Cropped, straight-edged |
| Sides | Curved | Straight |
| Consistency | Low β two faceting styles | High |
| At 1 ct, square | ~5.5 Γ 5.5 mm | ~5.5 Γ 5.5 mm |
| Reads as | Soft, antique-leaning | Crisp, contemporary |
| First question to ask | Crushed ice or chunky? | What is the ratio? |
Both come in square and elongated outlines, and neither ratio is printed on a report β divide length by width on the measurements line. Around 1.00β1.05 is square; 1.30β1.45 reads clearly elongated on either shape.
How each behaves in light
A radiant has a busy, energetic return β lots of facets, bright and lively in ordinary indoor light, and consistent enough that two well-cut radiants look broadly alike.
A crushed-ice cushion scatters light into many small glints, which reads as sparkle from a distance and slightly indistinct up close. A chunky cushion does the opposite: fewer, larger flashes with visible geometry, closer in character to an antique stone. If someone wants βan old-looking stoneβ, they almost always mean chunky.
One consequence specific to moissanite: dispersion is more than twice as strong as diamondβs, and it compounds with facet count. A crushed-ice cushion in moissanite is among the most conspicuous combinations available, while a chunky cushion is noticeably calmer for the same size. That is a real lever, and it costs nothing to choose.
Clarity and colour
Both are brilliant-faceted, so both are relatively forgiving β SI1 is usually eye-clean under a carat, VS2 a safe floor above two.
Two shape-specific notes. A crushed-ice cushion hides inclusions unusually well, because the scattered facets break up the view of the interior β genuinely the most forgiving common shape on clarity. A chunky cushion is less forgiving, since larger facets give a clearer window; treat it a little more like a step cut.
On colour, a radiantβs extra faceting concentrates body colour toward the corners, so in white gold or platinum stay at G or better. In warm metal, HβI reads white on both.
Setting them
- Radiant: a prong on each cropped corner β on the corner itself, not the flat side. The crop is the thinnest part of the girdle.
- Cushion: prongs at the four rounded corners. They are more robust than a cropped corner, but still the thinnest points.
- Four prongs to about two carats on either, six above.
- A cushion suits a bezel particularly well, because the rounded outline follows metal cleanly β a genuinely good option for anyone who would rather not think about it.
- Ask for the total width across the setting, not the stone dimensions. That is what decides whether a wedding band sits flush; run the straight-edge test against the CAD side elevation before casting.
Which to choose
Radiant if you want predictability, crisp geometry and liveliness, and you would rather not have to interrogate the faceting. It is the easier of the two to buy remotely.
Cushion if you want softness or an antique feel β but be specific about which kind, because the word alone will not get you the stone you pictured.
And on both: no laboratory grades cut on either shape. Rotating video in ordinary indoor light is the grading. Watch for a flat, dead centre, which is the commonest failure on badly cut cushions, and compare the measurements against the standard for the stated weight β larger than standard means the stone was spread shallow.
Keep reading
Frequently asked questions
What is the difference between a cushion and a radiant cut?
A cushion has rounded corners and curved sides; a radiant has straight sides and cropped corners, giving a crisper outline. The bigger practical difference is consistency β βcushionβ covers two very different faceting styles, while a radiant is far more predictable.
Why do two cushion cuts look so different?
Because the word describes only the outline. Crushed ice has many small facets and scatters light; chunky has fewer, larger facets and gives broad slow flashes. No report distinguishes them, so ask which it is before anything else.
Which shape hides inclusions best?
A crushed-ice cushion β the scattered facets break up the view of the interior, making it the most forgiving common shape on clarity. A chunky cushion is less forgiving, since larger facets give a clearer window into the stone.
Which is better for a moissanite?
It depends what you want. Moissaniteβs dispersion compounds with facet count, so a crushed-ice cushion is among the most conspicuous combinations available, while a chunky cushion reads noticeably calmer at the same size. Choosing between them costs nothing.
On a cushion, ask which kind before you ask anything else.
Crushed ice or chunky changes the stone more than a grade does β and no report records it.
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