Old Mine Cut Diamond: Pros, Cons & Light Leakage

The Old Mine cut has 58 facets in the classic count; our model, with its girdle facets, has 74. It sits on a rounded cushion outline with a wide 60.3% table, a steep 43.0° crown and a 44.38° pavilion.

We expected a dark stone, and the census agrees: it trails the T73 on brilliance by more than any other antique cut we measure in diamond.

Is an Old Mine cut diamond a good buy? Pros and cons

Pros

None that we measure. Its Tilt of 100 comes from keeping a small amount of light, so it does not count.

Cons

The least light face-up of our antique cuts 59 vs 93
Nearly a third of the light leaks 32 vs 2
A less regular pavilion 90 vs 100
A little less fire 72 vs 78

Compared with the T73 Round Brilliant in diamond and with the Old Mine 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 Old Mine 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, behind on 6.

Global74, the comparison 90, difference −16
Brilliance59, the comparison 93, difference −34
Fire72, the comparison 78, difference −6
Scintillation81, the comparison 80, difference +1
Spread98, the comparison 100, difference −2
Symmetry90, the comparison 100, difference −10
Shape-norm92, the comparison 100, difference −8
Tilt100, the comparison 92, 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 diamond gains in an Old Mine cut

We found no pro by our margins. The Tilt score is 100 against 92, but Tilt is the share of a stone's own light it keeps when tilted, and a stone at 59 brilliance keeps its share of a much smaller amount. Scintillation is level with the T73, at 81. Its appeal is the look: a broad cushion with large, soft facets.

The Old Mine's costs in diamond

The least light face-up of our antique cuts

Brilliance 59 against 93 for the T73 Round Brilliant in diamond: 34 points lower

The wide table and steep pavilion let light that comes straight down pass through the pavilion. In the face-up map, grey covers the corners and much of the cushion's flanks.

Old mine cut in diamond face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 59) — 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: In the same outline, our modern Cushion Cut returns 80 and the Peruzzi Cut Diamond 75.

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

Nearly a third of the light leaks

Leakage 32 against 2 for the T73 Round Brilliant in diamond: 30 points higher

Of the light in our census, 32% escapes through the back, where the T73 loses 2%. The strip shows the grey shrinking a little as the stone tips, but never going.

Old mine cut in diamond tilted 0 degrees: Light Return map, 34% 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.

Old mine cut in diamond tilted 10 degrees: Light Return map, 28% 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 leak is set by the angles, so a smaller stone leaks the same share. The Cushion Cut leaks 9%.

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

A less regular pavilion

Symmetry 90 against 100 for the T73 Round Brilliant in diamond: 10 points lower

The pavilion's facets vary more within the design than a modern round's: Symmetry 90.

Old Mine Cut · 74 facets · Symmetry 90

T73 Round Brilliant · 73 facets · Symmetry 100

Symmetry scores how regular the pavilion facets are within the design. Compare how evenly the facets repeat around each pavilion. Drawn from each cut's own model.

What helps: This is the design. The Old European Cut, the Old Mine's round successor, scores 100.

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

A little less fire

Fire 72 against 78 for the T73 Round Brilliant in diamond: 6 points lower

Fire 72 against 78: closer to the T73 than its brilliance is, but still behind.

Old mine cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 72) — 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.

What helps: For the most fire in an antique diamond, the Old Single Cut Diamond at 84.

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

Who an Old Mine cut diamond suits

The Old Mine suits someone who wants the look above all, and a period setting. Expect a softer, darker stone than any modern cut.

If you like the outline and want light, choose the modern Cushion Cut or the Peruzzi Cut Diamond. If an antique round will do, the Old European Cut Diamond comes within a few points of the T73.

Old Mine Cut Diamond: questions

Why does an Old Mine cut diamond look darker?

In our census 32% of its light leaves through the pavilion, against 2% for a modern round, and its brilliance is 59 against 93.

Old Mine or Old European cut diamond?

The Old European returns far more light: Brilliance 90 against 59, and it leaks 5% against 32%.

What does a 6.5 mm Old Mine cut diamond weigh?

About 1.21 ct across the width, from the model's measured volume.

Get the Old Mine Cut files

6 formatsMillimetresWatertight

Old Mine Cut 3D files

The Old Mine Cut as exact geometry: 74 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

Old Mine Cut cutting files

The Old Mine Cut as a faceting design: 58 + 16 girdles = 74 facets, 96 index, 4-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 Old Mine Cut: specifications, model and files

Old Mine Cut Diamond: an antique cushion that loses nearly a third of its light