Radiant Cut Emerald: Pros, Cons & Light Leakage

Our radiant model sets 74 brilliant-style facets inside a cropped rectangle 1.284 times as long as it is wide, and it is shallow: 53.8% from table to culet.

That shallow profile goes with a large face for the weight: only the marquise and the rectangle measure larger. It also leaks. No cut we measure in emerald loses a larger share of its light, and only the Old Single loses as much.

The diamond radiant is dim too, 32, so this model's proportions carry much of the problem. Emerald makes it worse: 22 here.

Should an emerald be radiant cut? Pros and cons

Pros

Lighter than a diamond radiant 1.21 vs 1.56 ct
A much larger face for its weight than a round 118 vs 100

Cons

A small share of the T73's light 22 vs 78
As leaky as any cut we measure in emerald 75 vs 22
Less fire than the diamond radiant 56 vs 77
Slightly less sparkle than a round 74 vs 80

Compared with the T73 Round Brilliant in emerald and with the Radiant Cut in diamond. A difference counts from 3 points (Brilliance, Fire, Tilt, Leakage), 5 (Scintillation, Symmetry), 4% (face-up size per carat) or 5% (weight); Tilt counts as a pro only for a stone within 5 points of the brilliance it is compared with. How we measure.

All eight scores against the T73

At a glance: the Radiant Cut in emerald (white) against the T73 Round Brilliant in emerald (dashed): solid white where it reaches further, hatched where it falls short. Each pro and con is explained, with pictures, below.

Against the T73 Round Brilliant in emerald: ahead on 3, behind on 5.

Global54, the comparison 73, difference −19
Brilliance22, the comparison 78, difference −56
Fire56, the comparison 39, difference +17
Scintillation74, the comparison 80, difference −6
Spread105, the comparison 100, difference +5
Symmetry99, the comparison 100, difference −1
Shape-norm25, the comparison 84, difference −59
Tilt100, the comparison 77, difference +23

Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring. Spread is the census's estimate from depth alone; the face-up size in the pros and cons is measured from each model's outline.

Open it in the Cut Performance Wheel

What emerald gains in a radiant cut

Lighter than a diamond radiant

1.21 ct at 6.5 mm, against 1.56 ct for the same cut in diamond (−23%)

A radiant 6.5 mm wide weighs 1.21 ct in emerald and 1.56 ct in diamond. The material makes the difference: beryl at 2.72, diamond at 3.52.

A Radiant Cut 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.

Try it yourself: Weights in all seven gemstones on the Radiant Cut page

A much larger face for its weight than a round

Face-up size 118 against 100 for the T73 Round Brilliant in emerald (T73 = 100): 18% more face-up area for the same weight

At 53.8% deep the radiant keeps little weight below the girdle, and its outline is longer than wide, so each carat spreads more face than the T73's. The figure is the model's own and the same in any stone.

Radiant Cut · 7.52 x 4.10 mm at 1.00 ct · Face-up size 118

T73 Round Brilliant · 7.06 mm at 1.00 ct · Face-up size 100

Both stones weigh 1.00 ct in emerald and are drawn to the same scale in millimetres, from each cut's own model. Face-up size is the outline's area per carat, with the T73 at 100: a deeper stone, or a rounder outline, spreads less area for its weight.

Try it yourself: See its size at 1.00 ct in emerald in the 3D Gemstone Simulator

The catch with a radiant emerald

A small share of the T73's light

Brilliance 22 against 78 for the T73 Round Brilliant in emerald: 56 points lower

22 against 78: the third-lowest of the cuts we measure in emerald, above only the Old Single and DG-Bowtie.

Radiant cut in emerald face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 22) — Red, green and blue = light returning to the eye; grey = light leaving through the pavilion. This is the head-on view; the Brilliance score averages a wider cone of light, so the score can differ from what one picture shows.

T73 round brilliant in emerald face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 78) — Red, green and blue = light returning to the eye; grey = light leaving through the pavilion. This is the head-on view; the Brilliance score averages a wider cone of light, so the score can differ from what one picture shows.

What helps: With cropped corners and a step plan, the Emerald Cut Emerald returns 58 in emerald; with rounded corners, the Cushion Cut Emerald returns 74.

Try it yourself: Open this Light Return map in the simulator

As leaky as any cut we measure in emerald

Leakage 75 against 22 for the T73 Round Brilliant in emerald: 53 points higher

75% of the light in our census leaves through the pavilion, against 22% for the T73 and 41% for the radiant in diamond. A shallow stone has less pavilion to turn light back up.

Radiant cut in emerald tilted 0 degrees: Light Return map, 75% of the face leaking — Each frame is the Light Return map with the stone tilted away from you by the angle shown; grey is light leaving through the pavilion. The share under each frame is that picture's own.

Radiant cut in emerald tilted 10 degrees: Light Return map, 70% of the face leaking — Each frame is the Light Return map with the stone tilted away from you by the angle shown; grey is light leaving through the pavilion. The share under each frame is that picture's own.

What helps: Leak share holds at any size, so cutting the radiant smaller will not help. The Emerald Cut Emerald leaks 35%, the Cushion Cut Emerald 25%.

Try it yourself: Tilt it yourself in the simulator's light map

Less fire than the diamond radiant

Fire 56 against 77 for the Radiant Cut in diamond: 21 points lower

56 against 77. It does beat the T73 in emerald, which scores 39, but the gap to diamond is the larger one, and that is where we count it.

Radiant cut in emerald face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 56) — Look at the coloured flashes: those are fire. Same light, same size, same face-up angle; rendered by our 3D Gemstone Simulator from each cut's own model.

Radiant cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 77) — Look at the coloured flashes: those are fire. Same light, same size, same face-up angle; rendered by our 3D Gemstone Simulator from each cut's own model.

Try it yourself: See the fire in the 3D Gemstone Simulator

Slightly less sparkle than a round

Scintillation 74 against 80 for the T73 Round Brilliant in emerald: 6 points lower

74 against 80: a small gap. The score is read from the facet plan in the census's model of the cut, which is why the diamond radiant scores the same.

Radiant Cut · 74 facets · Scintillation 74

T73 Round Brilliant · 73 facets · Scintillation 80

Scintillation follows the number of facets: more facets, more and smaller flashes as the stone moves. Count the facets in each crown. Drawn from each cut's own model.

Try it yourself: Compare the Scintillation spoke in the Cut Performance Wheel

Who a radiant emerald suits

The radiant in emerald suits a design that wants a large face for the weight and plenty of the stone's colour, and accepts a dim, glassy face. On light it is among the weakest cuts we measure in this stone.

For a cropped-corner rectangle with more light, the Emerald Cut Emerald. For a brilliant plan that keeps its light in emerald, the Cushion Cut Emerald or, as a round, DG-M5 Emerald.

Radiant Cut Emerald: questions

Is a radiant cut good for emerald?

As a source of light it disappoints, 22 to the T73's 78, and 75% of the light is lost. Its strength is face size per carat: 118 against 100.

Radiant or emerald cut for an emerald?

The Emerald Cut returns more light (58 against 22) and leaks less (35% against 75%). The radiant faces up larger per carat (118 against 105) and has more fire (56 against 36).

Does a radiant emerald sparkle?

Close to a round: Scintillation 74 against 80. The score depends on the facet plan alone and is the same for the radiant in diamond.

How heavy is a radiant emerald?

Measured 6.5 mm across its width, our radiant is 1.21 ct in emerald, where diamond would make it 1.56 ct.

Get the Radiant Cut files

6 formatsMillimetresWatertight

Radiant Cut 3D files

The Radiant Cut as exact geometry: 74 planar facets, real-world scale, ready for CAD, rendering, printing and casting.

STEPExact faceted solid for CAD
3DMRhino, closed mesh on its own layer
STLWatertight mesh for printing and casting
OBJMesh for modelling and rendering
FBXBlender, 3ds Max, Maya, Cinema 4D, Unity, Unreal
GLBWeb, AR and quick previews

€9.99 · Personal useBuy the 3D files

In preparation

Radiant Cut cutting files

The faceting design for the Radiant Cut is in preparation. It will include the GemCad file, the tier table and a printable diagram.

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More gemstones and cuts

Emerald: optical properties and the top ten cuts · The Radiant Cut: specifications, model and files

Radiant Cut Emerald: a large face for its weight, on a long, shallow stone