Rectangle Cut Amethyst: Pros, Cons & Face-up Size

The rectangle is the plainest of the step cuts: wide steps, square corners, nothing cropped. Our model has 45 facets, an L:W of 1.506, a 33.48° pavilion and 62.0% depth, close to the T73's 61.7%.

Depth for depth it is a match for the round, yet it covers far more area per carat. In diamond the same model scores 50 for brilliance; in amethyst, 24, a little under half as much.

Its fire, 50, beats the T73's 36 in quartz; against the same rectangle in diamond, fire is one of the cons below.

Is a rectangle cut right for amethyst? Pros and cons

Pros

A quarter lighter than diamond 1.58 vs 2.10 ct
Tied for the largest face per carat we measure 121 vs 100

Cons

A third of the T73's light 24 vs 72
Nearly three quarters of the light leaks 72 vs 28
Less fire than the diamond rectangle 50 vs 77
Fewer flashes than a round 63 vs 80

Compared with the T73 Round Brilliant in amethyst and with the Rectangle 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 Rectangle 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.

Against the T73 Round Brilliant in amethyst: ahead on 2, level on 2, behind on 4.

Global53, the comparison 70, difference −17
Brilliance24, the comparison 72, difference −48
Fire50, the comparison 36, difference +14
Scintillation63, the comparison 80, difference −17
Spread100, the comparison 100, difference 0
Symmetry100, the comparison 100, difference 0
Shape-norm31, the comparison 77, difference −46
Tilt100, the comparison 80, difference +20

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 rectangle cut

A quarter lighter than diamond

1.58 ct at 6.5 mm, against 2.10 ct for the same cut in diamond (−25%)

Amethyst's specific gravity of 2.65 against diamond's 3.52 means a rectangle cut to the same millimetres weighs about three quarters as much. A row of them in a bar or band stays light.

A Rectangle 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 Rectangle Cut page

Tied for the largest face per carat we measure

Face-up size 121 against 100 for the T73 Round Brilliant in amethyst (T73 = 100): 21% more face-up area for the same weight

No cut in our census covers more area per carat; the marquise ties it. Face-up size depends on the outline and the depth, not the material, so the rectangle shares that top place in every stone.

Rectangle Cut · 8.39 x 5.57 mm at 1.00 ct · Face-up size 121

T73 Round Brilliant · 7.12 mm at 1.00 ct · Face-up size 100

Both stones weigh 1.00 ct in amethyst 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 amethyst in the 3D Gemstone Simulator

The rectangle's costs in amethyst

A third of the T73's light

Brilliance 24 against 72 for the T73 Round Brilliant in amethyst: 48 points lower

The steps fall at 33.48°, well under the 40.4° guide minimum for round designs, and in quartz much of the light that reaches them passes straight through. In diamond, whose critical angle is far narrower, the same steps return about twice as much.

Rectangle cut in amethyst face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 24) — 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 amethyst face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (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: We have measured no steeper rectangle and promise none. The Emerald Cut Amethyst keeps a rectangle of steps and returns 53.

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

Nearly three quarters of the light leaks

Leakage 72 against 28 for the T73 Round Brilliant in amethyst: 44 points higher

Only the Old Single, the radiant and the Peruzzi leak a larger share in amethyst. The same model loses 32% in diamond, so most of this loss is quartz meeting a shallow step pavilion.

Rectangle cut in amethyst tilted 0 degrees: Light Return map, 77% 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.

Rectangle cut in amethyst tilted 10 degrees: Light Return map, 73% 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: A smaller rectangle leaks the same share. The Emerald Cut Amethyst loses 41% in a similar outline.

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

Less fire than the diamond rectangle

Fire 50 against 77 for the Rectangle Cut in diamond: 27 points lower

Broad steps return light in long flashes, and quartz has under a third of diamond's dispersion to colour them.

Rectangle cut in amethyst face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 50) — 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.

Rectangle 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.

What helps: DG-Anteros Amethyst reaches 54, a little more, with far more light.

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

Fewer flashes than a round

Scintillation 63 against 80 for the T73 Round Brilliant in amethyst: 17 points lower

45 long steps against the T73's 73 smaller facets, and our scintillation score counts facets: fewer facets, a lower score. The diamond version scores the same.

Rectangle Cut · 45 facets · Scintillation 63

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: The Emerald Cut Amethyst scores 72.

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

Who a rectangle cut amethyst suits

Choose the rectangle in amethyst for bars, side stones and minimalist settings, where a big, clean face for the weight matters more than light.

For a brighter rectangle of steps, the Emerald Cut Amethyst: more than twice the light, with less face per carat. If light comes first, DG-M5 Amethyst leads every cut in our amethyst census.

Rectangle Cut Amethyst: questions

Is a rectangle cut good for amethyst?

For size, yes: Face-up size 121, the largest we measure, level with the marquise. For light, it returns 24 against 72 for the T73.

Rectangle or emerald cut amethyst?

The emerald cut returns more light (53 against 24) and leaks less; the rectangle faces up larger per carat (121 against 105) and has more fire.

How much light does a rectangle amethyst leak?

Nearly three quarters: 72% in our census. The T73 loses 28% in amethyst, the diamond rectangle 32%.

What does a 6.5 mm wide rectangle amethyst weigh?

1.58 ct. In diamond: 2.10 ct.

Get the Rectangle Cut files

6 formatsMillimetresWatertight

Rectangle Cut 3D files

The Rectangle Cut as exact geometry: 45 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

Rectangle Cut cutting files

The Rectangle Cut as a faceting design: 41 + 4 girdles = 45 facets, 96 index, 2-fold mirror-image 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

Questions before you buy? Email us.

More gemstones and cuts

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

Rectangle Cut Amethyst: the largest face per carat we measure, level with the marquise