Old European Cut Peridot: Pros, Cons and Scores

Peridot has a refractive index of 1.650 to 1.690 and a dispersion of 0.020. Its critical angle, from the low end of that range, is 37.3°, so a round design needs a pavilion of at least 37.3° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.670, the midpoint of the published range, and a fire spread of 0.017, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.650, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the Old European Cut in peridot live. Peridot is strongly doubly refractive (birefringence up to 0.038), so its back facets can look doubled. Our census traces one index (1.670), so the doubling is not in these figures.

The Old European Cut has 74 facets, a table of 45.0% of its width and a total depth of 64.7% of its width; its pavilion mains sit at 41.5°. In peridot, the census returns 75 of 100 for brilliance and 51 for fire, against 90 and 53 for the T73, our benchmark, in the same stone; the same Old European Cut in diamond reads 90 and 74.

Is peridot good in an Old European? Pros and cons, measured

Pros

Lighter than the same cut in diamond 1.04 vs 1.09 ct

Cons

Less fire in peridot than in diamond 51 vs 74
Leaks more in peridot than in diamond 25 vs 5
Returns less light than the T73 in peridot 75 vs 90
Loses more light when tilted than in diamond 87 vs 93

Compared with the T73 Round Brilliant in peridot and with the Old European 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 Old European Cut in peridot (white) against the T73 Round Brilliant in peridot (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 peridot: ahead on 3, level on 1, behind on 4.

Global75, the comparison 80, difference −5
Brilliance75, the comparison 90, difference −15
Fire51, the comparison 53, difference −2
Scintillation81, the comparison 80, difference +1
Spread98, the comparison 100, difference −2
Symmetry100, the comparison 100, difference 0
Shape-norm116, the comparison 97, difference +19
Tilt87, the comparison 74, difference +13

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; these are the same census figures as our Cut Performance Index.

What the Old European Cut gains in peridot

Lighter than the same cut in diamond

1.04 ct at 6.5 mm, against 1.09 ct for the same cut in diamond (−5%)

Weight follows specific gravity: 3.35 for peridot against 3.52 for diamond, so the same model at the same size weighs 1.04 ct here and 1.09 ct in diamond, 6.5 mm across. Nothing about the light changes with it.

A Old European Cut 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.

Try it yourself: Weights in every gemstone on the Old European Cut page

What the Old European Cut gives up in peridot

Less fire in peridot than in diamond

Fire 51 against 74 for the Old European Cut in diamond: 23 points lower

Fire is the share of the returned light that splits into color at the exit facet: the census traces each exit again at the refractive index minus and plus the fire spread (0.017 in peridot) and counts a ray as fire when the two directions differ by more than 0.6°. The Old European Cut reads 51 against 74 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders peridot's fire live.

The fire figure is the census's, traced at the refractive index minus and plus the fire spread. See the fire in the 3D Gemstone Simulator: the Old European Cut in peridot under the sunny-day lighting.

What helps: the DG-Elongated Hexagon reads 83 for fire in peridot, the best of the cuts we score there.

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

Leaks more in peridot than in diamond

Leakage 25 against 5 for the Old European Cut in diamond: 20 points higher

Leakage is the share of the census rays that enter the stone and leave through the pavilion, or through the crown heading down. The Old European Cut leaks 25% in peridot against 5% for the same cut in diamond. Grey in the maps below is leaking light; the share under each picture is that picture's own.

Old european cut in peridot 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; gray is leakage. The share under each frame is that picture's own.

Old european cut in peridot 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; gray is leakage. The share under each frame is that picture's own.

What helps: the DG-M5 reads 1% for leakage in peridot, the best of the cuts we score there.

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

Returns less light than the T73 in peridot

Brilliance 75 against 90 for the T73 Round Brilliant in peridot: 15 points lower

Brilliance is the share of the 3,200 census rays that enter the stone and come back out of the crown towards the viewer. In peridot, whose critical angle is 37.3°, the Old European Cut returns 75 of 100 and the T73 90. The Old European Cut's pavilion mains sit at 41.5°, the T73's at 40.8°. The maps below show where each stone's light returns from and where it leaks.

Old european cut in peridot face-up Light Return map: red, green and blue show where the light returns from, gray shows where it leaks (Brilliance 75) — Red, green and blue = light returning to the eye; gray = leakage, light that leaves heading down or stays inside. 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 peridot face-up Light Return map: red, green and blue show where the light returns from, gray shows where it leaks (Brilliance 90) — Red, green and blue = light returning to the eye; gray = leakage, light that leaves heading down or stays inside. 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 DG-M5 reads 99 for brilliance in peridot, the best of the cuts we score there.

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

Loses more light when tilted than in diamond

Tilt 87 against 93 for the Old European Cut in diamond: 6 points lower

Tilt is how much of its face-up brilliance a stone keeps when the census tilts it 20° about its long axis, with 2,200 rays. The Old European Cut keeps 87 against 93 for the same cut in diamond. The tilt strips below show the maps at 0°, 10°, 20° and 30°, with each picture's own leak share under it.

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

Our verdict on the Old European Cut in peridot

Pick the Old European Cut in peridot for this: it weighs less than in diamond. The catch: it shows less fire than in diamond, leaks more than in diamond, returns less light than the T73 and loses more light when tilted than in diamond.

If that catch matters more to you, the DG-Elongated Hexagon reads 83 for fire in peridot, the best of the cuts we score there.

Every figure on this page is from our light census, traced at one refractive index: a simulation of the geometry, not a grading report. The 3D files and cutting files below are the same Old European Cut model we traced.

Old European Cut Peridot: questions

Is the Old European a good cut for peridot?

In our census the Old European Cut returns 75 of 100 for brilliance and 51 for fire in peridot, against 90 and 53 for the T73 in the same stone. Against that round and against the same cut in diamond it has 1 pro and 4 cons by our thresholds; the summary above names them.

What pavilion angle does peridot need?

At least 37.3° for a round design: peridot's critical angle is 37.3°, from the low end of its refractive index range, and head-on light has to reflect off both sides of the pavilion and leave through the table. The Old European Cut's pavilion mains sit at 41.5°.

How much does a Old European weigh in peridot?

At 6.5 mm across, 1.04 ct in peridot, against 1.09 ct for the same cut in diamond (-5%): peridot's specific gravity is 3.35, diamond's 3.52.

Can I see the Old European in peridot in 3D?

Yes: the 3D Gemstone Simulator renders it live, with peridot's own refractive index and dispersion. Peridot is traced by the same light census as the other gemstones, with its refractive index and fire spread derived from published values, so its scores are on the same scale; the pictures here are our Light Return tracer, and the Cut Performance Wheel sets it against any other cut and stone.

Get the Old European Cut files

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Old European Cut 3D files

The Old European 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
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OBJMesh for modeling and rendering
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GemCad96 index

Old European Cut cutting files

The Old European Cut as a faceting design: 58 + 16 girdles = 74 facets, 96 index, 8-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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Save with a bundle: the Old European Cut 3D and cutting files are also in Historic Cuts Complete, 6 cuts for €29.99 until 1 December, then €39.99 (€101.88 as single files). Buy the bundle.

Not sure the files open in your software? Get the cube free: the same six formats, for your email address, used only to send them (privacy).

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More gemstones and cuts

Peridot: optical properties and the top ten cuts · The Old European Cut: specifications, model and files

Old European Cut Peridot: lighter than the same cut in diamond