Old European Cut GGG: Pros, Cons and Scores

GGG has a refractive index of 1.970 and a dispersion of 0.045. Its critical angle, from the low end of that range, is 30.5°, so a round design needs a pavilion of at least 37.4° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.970, the midpoint of the published range, and a fire spread of 0.039, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.970, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the Old European Cut in GGG live.

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 GGG, the census returns 87 of 100 for brilliance and 69 for fire, against 98 and 76 for the T73, our benchmark, in the same stone; the same Old European Cut in diamond reads 90 and 74.

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

Pros

No figure ahead by our thresholds

Cons

Heavier than the same cut in diamond 2.18 vs 1.09 ct
Returns less light than the T73 in GGG 87 vs 98
Leaks more light than the T73 in GGG 12 vs 2
Less fire than the T73 in GGG 69 vs 76

Compared with the T73 Round Brilliant in GGG 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 GGG (white) against the T73 Round Brilliant in GGG (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 ggg: ahead on 3, level on 1, behind on 4.

Global85, the comparison 90, difference −5
Brilliance87, the comparison 98, difference −11
Fire69, the comparison 76, difference −7
Scintillation81, the comparison 80, difference +1
Spread98, the comparison 100, difference −2
Symmetry100, the comparison 100, difference 0
Shape-norm125, the comparison 105, difference +20
Tilt90, the comparison 82, difference +8

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 GGG

Against the T73 in GGG and the same cut in diamond, no figure of the Old European Cut is ahead by the thresholds above. Its figures are in the wheel and the FAQ; GGG ranks every cut we score in GGG.

What the Old European Cut gives up in GGG

Heavier than the same cut in diamond

2.18 ct at 6.5 mm, against 1.09 ct for the same cut in diamond (+100%)

Weight follows specific gravity: 7.05 for GGG against 3.52 for diamond, so the same model at the same size weighs 2.18 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

Returns less light than the T73 in GGG

Brilliance 87 against 98 for the T73 Round Brilliant in GGG: 11 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 GGG, whose critical angle is 30.5°, the Old European Cut returns 87 of 100 and the T73 98. 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 ggg face-up Light Return map: red, green and blue show where the light returns from, gray shows where it leaks (Brilliance 87) — 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 ggg face-up Light Return map: red, green and blue show where the light returns from, gray shows where it leaks (Brilliance 98) — 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-Broken Hearts and Arrows reads 98 for brilliance in GGG, the best of the cuts we score there.

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

Leaks more light than the T73 in GGG

Leakage 12 against 2 for the T73 Round Brilliant in GGG: 10 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 12% in GGG against 2% for the T73 in GGG. Grey in the maps below is leaking light; the share under each picture is that picture's own.

Old european cut in ggg tilted 0 degrees: Light Return map, 17% 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 ggg tilted 10 degrees: Light Return map, 12% 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-Broken Hearts and Arrows reads 2% for leakage in GGG, the best of the cuts we score there.

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

Less fire than the T73 in GGG

Fire 69 against 76 for the T73 Round Brilliant in GGG: 7 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 (0.039 in GGG) and counts a ray as fire when the two directions differ by more than 0.6°. The Old European Cut reads 69 against 76 for the T73 in GGG. The figure is the census's; the 3D Gemstone Simulator renders GGG'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 GGG under the sunny-day lighting.

What helps: the Oval Cut reads 96 for fire in GGG, the best of the cuts we score there.

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

Our verdict on the Old European Cut in GGG

Against the T73 in GGG and the same cut in diamond, no figure of the Old European Cut is ahead by our thresholds. The catch: it weighs more than in diamond, returns less light than the T73, leaks more light than the T73 and shows less fire than the T73.

If that catch matters more to you, the DG-Broken Hearts and Arrows reads 98 for brilliance in GGG, 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 GGG: questions

Is the Old European a good cut for GGG?

In our census the Old European Cut returns 87 of 100 for brilliance and 69 for fire in GGG, against 98 and 76 for the T73 in the same stone. Against that round and against the same cut in diamond it has 0 pros and 4 cons by our thresholds; the summary above names them.

What pavilion angle does GGG need?

At least 37.4° for a round design: GGG's critical angle is 30.5°, 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 GGG?

At 6.5 mm across, 2.18 ct in GGG, against 1.09 ct for the same cut in diamond (+100%): GGG's specific gravity is 7.05, diamond's 3.52.

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

Yes: the 3D Gemstone Simulator renders it live, with GGG's own refractive index and dispersion. GGG 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

6 formatsMillimetersWatertight

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
STLWatertight mesh for printing and casting
OBJMesh for modeling 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 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

€6.99 · Personal useBuy the cutting files

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).

Questions before you buy? Email us.

More gemstones and cuts

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

Old European Cut GGG: what our light census measures