Oval Cut Diamond: Pros, Cons & Light Leakage

An oval is a round brilliant pulled out along one axis, facets and all. The oval we measured runs to a ratio of 1.331, 93 facets and a depth of 64.0%, over a 40.99° pavilion.

In diamond it is a cut of extremes. Its fire is second only to DG-Elongated Hexagon among the cuts we measure; its brilliance is about half the T73's. Those two numbers are the story of this page.

Ovals are said to face up larger than a round of the same weight. In our census the oval's spread is 99 against 100 for the T73: level.

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

Cons

About half the light of the T73 47 vs 93
More than a quarter of the light leaks 27 vs 2

Compared with the T73 Round Brilliant 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 diamond (white) against the T73 Round Brilliant in diamond (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 diamond: ahead on 2, level on 1, behind on 5.

Global75, the comparison 90, difference −15
Brilliance47, the comparison 93, difference −46
Fire92, the comparison 78, difference +14
Scintillation87, the comparison 80, difference +7
Spread99, the comparison 100, difference −1
Symmetry98, the comparison 100, difference −2
Shape-norm54, the comparison 100, difference −46
Tilt92, the comparison 92, difference 0

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 diamond gains in an oval

Far more fire than the T73

Fire 92 against 78 for the T73 Round Brilliant in diamond: 14 points higher

Only one cut we measure in diamond shows more. Stretching the plan sets facets at many different angles to the eye, and light leaving them spreads into colour.

Oval cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 92) — 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 diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 78) — 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

More scintillation than the T73

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

93 facets against the T73's 73, laid out along the length: more flashes as the stone moves.

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 oval's costs in diamond

About half the light of the T73

Brilliance 47 against 93 for the T73 Round Brilliant in diamond: 46 points lower

The largest brilliance gap on our diamond pages. Along the narrow sides the pavilion meets light at angles that let it through rather than reflect it. Many ovals show this as a dark band across the middle, the bowtie; we do not measure that band.

Oval cut in diamond face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 47) — 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 diamond face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 93) — 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: Among elongated cuts in diamond, the Marquise Cut Diamond returns the most light, 64. For far more, a round: the T73 Round Brilliant Diamond.

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

More than a quarter of the light leaks

Leakage 27 against 2 for the T73 Round Brilliant in diamond: 25 points higher

More than a quarter of the light, 27%, goes out through the oval's pavilion in our census; the T73 lets 2% through. Its 40.99° pavilion figure sits above the 38.9° guide minimum, so a steeper pavilion is not the remedy our data supports.

Oval cut in diamond tilted 0 degrees: Light Return map, 31% 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.

Oval cut in diamond tilted 10 degrees: Light Return map, 31% 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: The share is the same at any size. The Marquise Cut Diamond leaks 17% and keeps an elongated outline; the T73 leaks 2%.

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

Who an oval diamond suits

Choose the oval for colour: an elongated diamond with fire near the top of our scale and more sparkle than a round. Accept that it returns about half the light of the T73, and look at the stone face-up for a bowtie before buying.

For an elongated stone with more light, the Marquise Cut Diamond; for a round's light with some extra fire, DG-Miliano Diamond at 82.

Oval Cut Diamond: questions

Does an oval diamond have more fire than a round?

Yes, much more: Fire 92 against 78 for the T73 Round Brilliant in our census.

Why do oval diamonds look darker in the middle?

We do not measure the bowtie directly. Our census shows the oval leaking 27% of its light against 2% for a round, and leaking light reads as dark.

Does an oval diamond look bigger than a round?

Not by our spread score at the same weight: 99 against 100. Its length can make it read larger.

What does a 6.5 mm wide oval diamond weigh?

1.42 ct, measured across the width; the stone is 1.331 times as long.

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

€9.99 · Personal useBuy the 3D files

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

€9.99 · Personal useBuy the cutting files

Questions before you buy? Email us.

More gemstones and cuts

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

Oval Cut Diamond: the second-most fire of any cut we measure