Lab Grown Diamonds
Princess or Radiant: Corners Decide It
Two square-ish brilliants that look similar in a photograph and behave differently on a hand for one structural reason.
Written by the Mapple Gems workshop, Surat Β· Updated 6 October 2026
Short answer
A princess has four sharp 90-degree corners; a radiant has four cropped ones. That single difference decides most of it. The princess faces up slightly larger per carat and looks crisper, but its corners are the thinnest, most vulnerable points in any shape and must be covered. The radiant sacrifices a little size for far more forgiving corners and more brilliance. Neither receives a cut grade, so video is mandatory on both.
These two get shortlisted together constantly because both read as geometric alternatives to a round. The choice between them is less about looks than most people expect.
A princess cutβs corners are the single most vulnerable geometry in diamond β a right angle where the girdle runs to almost nothing β and the entire practical case between these two shapes follows from that. At a sharp corner, two girdle edges meet at ninety degrees and the material tapers to a point with nothing behind it. All diamonds have cleavage planes and can chip, and that corner is where an impact concentrates. The radiant cut exists partly as the answer: its corners are cropped, replacing each right angle with a short bevelled edge, and that small change removes the fragile point entirely. Neither shape is a bad choice β but a princess is a setting decision in a way a radiant is not. Every corner needs its own prong, placed on the corner rather than on the flat side, which is a surprisingly common error and leaves the exact spot that needed metal uncovered. On a working hand, or for anyone who would rather not think about it, that argues for a radiant, a V-prong arrangement, or a bezel. It is also why we would not set a princess in a design that leaves the corners open, whatever the render looks like.
Side by side
| Princess | Radiant | |
|---|---|---|
| Corners | Sharp, 90Β° | Cropped |
| At 1 ct | ~5.5 Γ 5.5 mm | ~6.5 Γ 5.0 mm (rectangular) |
| Typical ratio | 1.00 β 1.05 | 1.00 square or 1.25β1.45 |
| Character | Crisp, sharp, contemporary | Softer, livelier, warmer |
| Chip risk | Higher β cover the corners | Lower |
| Wedding band | Straight usually fits | Straight if square; contour if long |
The radiant comes in both square and rectangular outlines, which the princess essentially does not β so if you want a geometric shape that also lengthens the finger, the radiant is the one that does it. Derive the ratio yourself: it is never printed.
How they behave in light
Both are brilliant-faceted rather than step cuts, so both flash and scintillate β this is not the emerald-versus-Asscher conversation.
A princess is cut with a distinctive chevron pattern in the pavilion, which gives it a sharp, contained sparkle with clear geometry. A radiant has more facets and a slightly more scattered, energetic return β noticeably livelier in ordinary indoor light, which is where you will actually see it.
One consequence worth knowing on colour: a radiantβs extra faceting concentrates body colour toward the corners, so a warmer grade shows a little more than in a princess of the same colour. In yellow or rose gold that is invisible; in white gold or platinum, stay at G or better on a radiant.
Clarity, and where inclusions can hide
Both are relatively forgiving because both scintillate, so SI1 is usually eye-clean under a carat and VS2 is a safe floor above two.
What matters more is position, and here the shapes agree: an inclusion at a corner is hidden by the prong that has to be there anyway, and one under the table is in the clearest line of sight. Open the plot diagram β it takes two minutes and a well-placed SI1 routinely beats a badly placed VS2 that costs more.
One structural exception applies with more force to the princess: a feather reaching the surface at or near a corner is worth a direct question, because that is exactly where impact stress concentrates.
Setting each one
- Princess: a prong on each corner, ideally V-shaped so metal wraps both faces of the point. Never prongs on the flat sides only. A bezel or half-bezel that covers the corners is the most protective option.
- Radiant: a prong on each cropped corner as well β the crop is more robust but still the thinnest part of the girdle.
- Both: ask for the total width across the setting, which is what decides whether a band sits flush, not the stone dimensions.
- Both: shank at 1.8β2Β mm measured at the base. A square stone loads a shank unevenly as the hand grips.
- Both: run the straight-edge test against the CAD side elevation before casting to decide straight band or contour.
Which to choose
Princess if you want the crispest geometry and the most stone per carat in a square outline, and you are happy to insist on corner coverage. It is the sharper, more contemporary of the two.
Radiant if you want liveliness, a more forgiving stone, or a rectangular outline that lengthens the finger. It is the easier ring to own and the better choice for hands that work.
And on both: no laboratory grades cut on either shape. Rotating video in ordinary indoor light is the grading β look for crisp facet junctions, no permanently dark zone through rotation, a symmetrical outline, and measurements that match the standard for the stated weight rather than exceeding it.
Keep reading
Frequently asked questions
What is the difference between a princess and a radiant cut?
Corners. A princess has four sharp 90-degree corners; a radiant has four cropped ones. The princess faces up slightly larger per carat and looks crisper; the radiant is livelier, more forgiving, and comes in rectangular outlines as well as square.
Do princess cut diamonds chip easily?
The corners are the most vulnerable geometry in diamond β a right angle where the girdle tapers to almost nothing, and all diamonds have cleavage planes. It is a setting question rather than a reason to avoid the shape: a prong on each corner, V-shaped, or a bezel.
Which sparkles more?
The radiant, generally β more facets give a more scattered, energetic return, noticeably livelier in ordinary indoor light. The princess has a sharper, more contained sparkle from its chevron pavilion pattern. Both are brilliant-faceted rather than step cuts.
Do either get a cut grade?
No β no laboratory grades cut on any fancy shape. Rotating video in ordinary indoor light is the grading: crisp facet junctions, no permanently dark zone through rotation, a symmetrical outline, and measurements matching rather than exceeding the standard for the weight.
On a princess, check the render for a prong on every corner.
Prongs on the flat sides is the commonest error on this shape, and it leaves the one place that needed metal uncovered.
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