Oval Cut Amethyst: Pros, Cons & Fire

The oval is the brilliant plan stretched along one axis, here to 1.331 times as long as it is wide. The model carries 93 facets, with pavilion mains at 40.99° and a total depth of 64.0%.

In amethyst it nearly doubles the T73's fire, and it sparkles a little more. The cost is light: it returns 52 where the T73 returns 72, and it leaks more than the same oval in diamond.

One pair of figures looks odd. The amethyst oval returns slightly more light than the diamond oval, 52 against 47, while leaking more. The two scores measure different things, and we print both as the census gives them.

Is an oval a good cut for amethyst? Pros and cons

Pros

Nearly twice the round's fire 69 vs 36
Lighter than diamond 1.07 vs 1.42 ct
A little more sparkle than the T73 87 vs 80

Cons

Less light than the T73 52 vs 72
Holds less light when tipped than in diamond 74 vs 92
More leakage than the diamond oval 43 vs 27

Compared with the T73 Round Brilliant in amethyst and with the Oval 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 Oval 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, behind on 6.

Global68, the comparison 70, difference −2
Brilliance52, the comparison 72, difference −20
Fire69, the comparison 36, difference +33
Scintillation87, the comparison 80, difference +7
Spread99, the comparison 100, difference −1
Symmetry98, the comparison 100, difference −2
Shape-norm61, the comparison 77, difference −16
Tilt74, the comparison 80, difference −6

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 an oval

Nearly twice the round's fire

Fire 69 against 36 for the T73 Round Brilliant in amethyst: 33 points higher

No cut we measure in amethyst sends more coloured light to the eye. Stretched facets throw light out at a wider spread of angles than a round's.

Oval cut in amethyst face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 69) — 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.

T73 round brilliant in amethyst face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 36) — 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

Lighter than diamond

1.07 ct at 6.5 mm, against 1.42 ct for the same cut in diamond (−25%)

An oval 6.5 mm wide, and about 1.331 times as long, weighs 1.07 ct in amethyst against 1.42 ct in diamond.

A Oval 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 Oval Cut page

A little more sparkle than the T73

Scintillation 87 against 80 for the T73 Round Brilliant in amethyst: 7 points higher

93 facets against 73 on the round, and our scintillation score rises with the facet plan.

Oval Cut · 93 facets · Scintillation 87

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

The catch with an oval amethyst

Less light than the T73

Brilliance 52 against 72 for the T73 Round Brilliant in amethyst: 20 points lower

Stretching the plan changes the pavilion's slope along the length and across the width, and part of the face stops sending light back. Ovals are prone to a darker band across the middle, the bow-tie, which we do not measure.

Oval cut in amethyst face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 52) — 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: Of the brilliant-cut elongated shapes in amethyst, none returns more; the Pear Cut Amethyst matches it at 52. For light first, a round: DG-M5 Amethyst at 85.

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

Holds less light when tipped than in diamond

Tilt 74 against 92 for the Oval Cut in diamond: 18 points lower

Tipped by 20°, it keeps 74 of its face-up light, against 92 for the diamond oval.

Oval cut in amethyst tilted 0 degrees: Light Return map, 40% of the face leaking — Tilt is how much of its own face-up light a stone keeps when tilted. 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.

Oval cut in amethyst tilted 10 degrees: Light Return map, 47% of the face leaking — Tilt is how much of its own face-up light a stone keeps when tilted. 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: Among the oval, pear, teardrop and marquise, the oval already holds best. The T73 Round Brilliant Amethyst keeps 80.

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

More leakage than the diamond oval

Leakage 43 against 27 for the Oval Cut in diamond: 16 points higher

43% of the light in our census leaves through the pavilion in amethyst, 27% in diamond. Quartz's critical angle of about 40.4° gives the light more ways out.

What helps: The pavilion is at 40.99°, above the 40.4° guide minimum worked out for rounds, so steepening is not what our data supports. The Pear Cut Amethyst leaks 39%, DG-M5 Amethyst 15%.

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

Who an oval amethyst suits

For an amethyst that shows coloured flashes as well as its own purple, this is the cut we would choose: the most fire we measure in quartz and a little more sparkle than the round.

Amethyst's colour often sits in zones in the rough, and an oval's length gives a cutter room to orient the deepest band across the face.

If light matters more than fire, DG-M5 Amethyst returns the most in amethyst.

Oval Cut Amethyst: questions

Is oval a good cut for amethyst?

It is our top amethyst cut for fire, 69 to the T73's 36, and a weaker one for light, 52 to 72.

Does an oval amethyst have a bow-tie?

Ovals are prone to one, a darker band across the middle. We do not measure it, so we cannot score this one.

Oval or round amethyst?

The oval has more fire (69 against 36); the T73 round returns more light (72 against 52) and leaks less (28% against 43%).

What does a 6.5 mm wide oval amethyst weigh?

1.07 ct, against 1.42 ct for the same oval in diamond.

Get the Oval Cut files

6 formatsMillimetresWatertight

Oval Cut 3D files

The Oval Cut as exact geometry: 97 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

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GemCad96 index

Oval Cut cutting files

The Oval Cut as a faceting design: 73 + 20 girdles = 93 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

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Questions before you buy? Email us.

More gemstones and cuts

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

Oval Cut Amethyst: the most fire of any cut we measure here