Radiant Square Cut Amethyst: a cropped-corner square that weighs a quarter less than diamond

Brilliance 51 · Fire 20 · Scintillation 66 · in our census, where the T73 scores 72 · 36 · 80 in amethyst

In diamond this square scores 72 for brilliance. In amethyst it loses nearly a third of that, and most of its fire.

See it in the simulatorGet the files
The Radiant Square Cut in amethyst, rendered at an angle in our 3D Gemstone Simulator under studio light
Rendered in our 3D Gemstone Simulator from the Radiant Square Cut model, 1.00 ct, studio light.

Radiant Square Cut Amethyst

The radiant square carries a brilliant facet plan under a square outline with cropped corners. Our model has 49 facets and is deep, 72.8% from table to culet, with a 34.64° pavilion.

That pavilion sits under amethyst's 40.4° guide minimum for rounds. The diamond version returns 72; in quartz the same model keeps 51.

The deep build also costs a little size for weight: per carat it faces up smaller than the round, 91 against 100.

How does amethyst do as a radiant square? Pros and cons

Pros

Cons

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

Performance wheel: Radiant Square Cut in amethyst, against the T73 Round Brilliant in amethyst as an outline. Solid white marks where it reaches further, hatching where it falls short. The scores are listed below.50100Global−13Brilliance−21Fire−16Scintillation−14Spread+1Symmetry0Shape-norm−17Tilt+7

Against the T73 Round Brilliant in amethyst: ahead on 2, level on 1, behind on 5.

  • Global57, the comparison 70, difference −13
  • Brilliance51, the comparison 72, difference −21
  • Fire20, the comparison 36, difference −16
  • Scintillation66, the comparison 80, difference −14
  • Spread101, the comparison 100, difference +1
  • Symmetry100, the comparison 100, difference 0
  • Shape-norm60, the comparison 77, difference −17
  • Tilt87, the comparison 80, difference +7
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 amethyst gains in a radiant square

A quarter lighter than diamond, size for size

1.22 ct at 6.5 mm, against 1.62 ct for the same cut in diamond (−25%)

Amethyst's specific gravity is 2.65 to diamond's 3.52. A deep square like this one carries a lot of stone below the girdle, and in quartz all of it weighs a quarter less.

Amethyst1.22 ctDiamond1.62 ct
A Radiant Square 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 Square Cut page

The radiant square's costs in amethyst

About a third of the diamond's fire

Fire 20 against 62 for the Radiant Square Cut in diamond: 42 points lower

The diamond radiant square scores 62 for fire; in amethyst the same facets reach only 20. Only the Portuguese Bird's Nest and the Peruzzi score less fire in amethyst.

Radiant square cut in amethyst face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 20)

Radiant Square Cut in amethyst · Fire 20

Radiant square cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 62)

Radiant Square Cut in diamond · Fire 62

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.

What helps: Of the cuts within ten points of the T73's brilliance in amethyst, DG-Anteros Amethyst has the most fire, 54; DG-M5 Amethyst, brighter still, scores 50.

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

Nearly half the light leaks

Leakage 47 against 12 for the Radiant Square Cut in diamond: 35 points higher

The diamond version loses 12% of its light through the back; in amethyst the share is about four times that. In the picture, the diamond's strip is a fifth grey or less in every frame.

Radiant Square Cut in amethyst · Leakage 47

Radiant square cut in amethyst tilted 0 degrees: Light Return map, 52% of the face leaking0° · 52% leak
Radiant square cut in amethyst tilted 10 degrees: Light Return map, 53% of the face leaking10° · 53% leak
Radiant square cut in amethyst tilted 20 degrees: Light Return map, 46% of the face leaking20° · 46% leak
Radiant square cut in amethyst tilted 30 degrees: Light Return map, 49% of the face leaking30° · 49% leak

Radiant Square Cut in diamond · Leakage 12

Radiant square cut in diamond tilted 0 degrees: Light Return map, 18% of the face leaking0° · 18% leak
Radiant square cut in diamond tilted 10 degrees: Light Return map, 16% of the face leaking10° · 16% leak
Radiant square cut in diamond tilted 20 degrees: Light Return map, 16% of the face leaking20° · 16% leak
Radiant square cut in diamond tilted 30 degrees: Light Return map, 20% of the face leaking30° · 20% leak
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: We have not measured a steeper radiant square, and promise none. The Square Cut Amethyst brilliant leaks 29% in a square outline.

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

Less light than the T73

Brilliance 51 against 72 for the T73 Round Brilliant in amethyst: 21 points lower

Light that reaches a 34.64° pavilion in quartz falls inside the critical angle more often than in diamond, so part of it leaves through the back. The cushion, the square brilliant and the Asscher all return more in amethyst.

Radiant square cut in amethyst face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 51)

Radiant Square Cut in amethyst · Brilliance 51

T73 round brilliant in amethyst face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 72)

T73 Round Brilliant in amethyst · Brilliance 72

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: In a square, the Cushion Cut Amethyst returns 69, the most of any non-round cut we measure in amethyst.

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

Fewer flashes than a round

Scintillation 66 against 80 for the T73 Round Brilliant in amethyst: 14 points lower

49 facets against the T73's 73. Sparkle on our scale follows the facet plan, not the stone: the diamond version scores the same.

Radiant Square Cut · 49 facets · Scintillation 66

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.

What helps: For more sparkle as well as more light, the cushion again: 85.

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

Who a radiant square amethyst suits

The radiant square suits an amethyst centre stone where cropped corners matter more than sharp ones and the colour, not the fire, is the show. Its cut-away corners spare quartz, at hardness 7, the points a princess has.

For more light in a square amethyst, the Cushion Cut Amethyst; for less leakage, the Square Cut Amethyst brilliant.

Radiant Square Cut Amethyst: questions

Is a radiant square cut good for amethyst?

It trails the round on light, 51 against 72, and leaks 47% of the light in our census. It holds steady when tipped: Tilt 87.

Radiant square or princess amethyst?

The radiant square returns a little more light (51 against 45) and leaks a little less (47% against 50%); the princess sparkles more (78 against 66) and has more fire.

Does a radiant square amethyst face up small for its weight?

Slightly: Face-up size 91 against 100 for the T73, measured from the outline at the same weight. It is a deep cut, 72.8%.

What does a 6.5 mm radiant square amethyst weigh?

1.22 ct; a diamond one, 1.62 ct.

Get the Radiant Square Cut files

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Radiant Square Cut 3D files

The Radiant Square Cut as exact geometry: 49 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
GemCad96 index

Radiant Square Cut cutting files

The Radiant Square Cut as a faceting design: 41 + 8 girdles = 49 facets, 96 index, 4-fold symmetry, ready for the machine.

  • .ascGemCad design file, 96 index gear
  • .csvTier table: angles, indices and cutting order
  • DiagramPrintable faceting diagram
€9.99 · Personal useBuy the cutting files

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More gemstones and cuts

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

Other cuts in amethyst

The Radiant Square Cut in other gemstones