Trillion Cut Amethyst: a large face for its weight, with little leakage for a fancy

Brilliance 60 · Fire 44 · Scintillation 80 · in our census, where the T73 scores 72 · 36 · 80 in amethyst

A shallow, three-sided brilliant that faces up large and leaks barely more than the T73 does in quartz. Its catch is the one every amethyst shares: little fire.

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

Trillion Cut Amethyst

The trillion is a three-sided brilliant whose sides bow gently outward. Our model is shallow, 50.7% deep, with a 56.6% table, a 36.0° crown and a 31.91° pavilion, 73 facets in all.

That shallow build gives it its face: at the same weight it shows more than the T73. It also makes a light stone, 0.60 ct at 6.5 mm, the lightest for its width of any cut on our amethyst pages.

Its leakage, 30%, is close to the T73's 28%; the light it does lose shows up as brilliance a little under the round's.

Is a trillion cut good for amethyst? Pros and cons

Pros

Cons

Compared with the T73 Round Brilliant in amethyst and with the Trillion Cut in diamond. A difference counts from 3 points (Brilliance, Fire, Tilt, Leakage), 5 (Scintillation, Symmetry), 2 (Spread) 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 Trillion 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: Trillion 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−2Brilliance−12Fire+8Scintillation0Spread+7Symmetry0Shape-norm−7Tilt+8

Against the T73 Round Brilliant in amethyst: ahead on 3, level on 2, behind on 3.

  • Global68, the comparison 70, difference −2
  • Brilliance60, the comparison 72, difference −12
  • Fire44, the comparison 36, difference +8
  • Scintillation80, the comparison 80, difference 0
  • Spread107, the comparison 100, difference +7
  • Symmetry100, the comparison 100, difference 0
  • Shape-norm70, the comparison 77, difference −7
  • Tilt88, the comparison 80, difference +8
Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring.
Open it in the Cut Performance Wheel

What amethyst gains in a trillion

A quarter lighter than diamond

0.60 ct at 6.5 mm, against 0.80 ct for the same cut in diamond (−25%)

The same trillion in diamond would weigh 0.80 ct at 6.5 mm. Quartz's specific gravity of 2.65, against 3.52, accounts for the difference.

Amethyst0.60 ctDiamond0.80 ct
A Trillion 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 Trillion Cut page

Faces up larger than a round

Spread 107 against 100 for the T73 Round Brilliant in amethyst: 7 points higher

At 50.7% deep the trillion puts more of its weight into width; for the same carat weight it shows more face than the T73.

Trillion Cut · 7.70 mm at 1.00 ct · Spread 107

T73 Round Brilliant · 7.12 mm at 1.00 ct · Spread 100

Both stones weigh 1.00 ct in amethyst and are drawn to the same scale, from each cut's own model. Spread is face-up size per carat: a deeper stone carries more weight below the girdle and looks smaller for its weight.

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

The catch with a trillion amethyst

Half the diamond version's fire

Fire 44 against 87 for the Trillion Cut in diamond: 43 points lower

With dispersion of 0.013, quartz gives the crown little colour to spread; the diamond trillion scores 87.

Trillion cut in amethyst face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 44)

Trillion Cut in amethyst · Fire 44

Trillion cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 87)

Trillion Cut in diamond · Fire 87

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: The Triangle Cut reaches 61 in amethyst, the Oval Cut Amethyst 69.

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

More leakage than in diamond

Leakage 30 against 13 for the Trillion Cut in diamond: 17 points higher

In amethyst 30% of the light leaves through the pavilion, where diamond loses 13%. For a fancy shape in quartz that is still low: of the cuts we measure here, only five rounds and the square brilliant leak less.

Trillion Cut in amethyst · Leakage 30

Trillion cut in amethyst tilted 0 degrees: Light Return map, 33% of the face leaking0° · 33% leak
Trillion cut in amethyst tilted 10 degrees: Light Return map, 36% of the face leaking10° · 36% leak
Trillion cut in amethyst tilted 20 degrees: Light Return map, 42% of the face leaking20° · 42% leak
Trillion cut in amethyst tilted 30 degrees: Light Return map, 59% of the face leaking30° · 59% leak

Trillion Cut in diamond · Leakage 13

Trillion cut in diamond tilted 0 degrees: Light Return map, 16% of the face leaking0° · 16% leak
Trillion cut in diamond tilted 10 degrees: Light Return map, 17% of the face leaking10° · 17% leak
Trillion cut in diamond tilted 20 degrees: Light Return map, 19% of the face leaking20° · 19% leak
Trillion cut in diamond tilted 30 degrees: Light Return map, 29% of the face leaking30° · 29% 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: No three-sided cut we measure in amethyst leaks less. DG-M5 Amethyst leaks 15%.

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

Less light than the T73

Brilliance 60 against 72 for the T73 Round Brilliant in amethyst: 12 points lower

A 31.91° pavilion is well under the round's guide angle, and a triangle's corners return less than a circle's rim.

Trillion cut in amethyst face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 60)

Trillion Cut in amethyst · Brilliance 60

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: The straight-sided Trilliant Cut Amethyst returns 63, a little more, at a cost in symmetry.

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

Who a trillion amethyst suits

Choose the trillion for an amethyst solitaire or side stones that should look large for their weight, with less leakage than most fancy shapes.

Its shallow depth suits a low setting, and the bowed sides protect the corners better than a straight-sided trilliant's.

A shallow stone shows paler colour than a deep one cut from the same rough, so the trillion suits well-saturated amethyst.

For a little more light in three sides, the Trilliant Cut Amethyst; for fire, the Oval Cut Amethyst.

Trillion Cut Amethyst: questions

Is a trillion cut good for amethyst?

Yes, for face-up size and low leakage: Spread 107, leakage 30%. Brilliance is 60 against 72 for the T73.

Trillion or trilliant amethyst?

The trillion leaks less (30% against 36%) and has a regular pavilion (Symmetry 100 against 62); the trilliant returns a little more light.

Does a trillion amethyst look larger than a round?

For its weight, yes: Spread 107 against 100 for the T73. At 50.7% deep it carries its weight in width rather than below the girdle.

What does a 6.5 mm trillion amethyst weigh?

0.60 ct, against 0.80 ct in diamond.

Get the Trillion Cut files

6 formatsMillimetresWatertight

Trillion Cut 3D files

The Trillion Cut as exact geometry: 73 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
GemCad120 index

Trillion Cut cutting files

The Trillion Cut as a faceting design: 61 + 12 girdles = 73 facets, 120 index, 3-fold symmetry, ready for the machine.

  • .ascGemCad design file, 120 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 Trillion Cut: specifications, model and files

Other cuts in amethyst

The Trillion Cut in other gemstones