---
title: "Old Mine Cut Tanzanite: Pros, Cons and Scores"
description: "Old Mine Cut in tanzanite: brilliance 47, fire 38, leakage 52%, 1 pro and 4 cons against the T73, from our ray-traced light census."
url: https://digitalgemology.com/gemstones/tanzanite/old-mine
image: https://digitalgemology.com/img/stone-cuts/old-mine-tanzanite-og.jpg?v=66f4fb69
---

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# Old Mine Cut Tanzanite: lighter than the same cut in diamond

**Buy (instant download, personal-use license):** [Old Mine Cut 3D files, €9.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/5b3b75f2-db63-4e1c-8acc-ed119e91984a) · [Old Mine Cut cutting files, €6.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/54ae00b8-0467-47be-a84f-354652bd5c37) · [Buy the bundle](https://digitalgemology.lemonsqueezy.com/checkout/buy/dcf2c236-6e04-4292-8040-9d21ac6446d1?checkout%5Bdiscount_code%5D=HISTORIC25) · [Get the cube free](https://digitalgemology.lemonsqueezy.com/checkout/buy/2d1ab55f-2bd6-4897-a4cd-f3320f54e99e)

Brilliance 47 · Fire 38 · Scintillation 81 · in our census, where the T73 scores 92 · 47 · 80 in tanzanite

How the Old Mine Cut handles light in tanzanite, measured: brilliance 47, fire 38 and 52% leakage, set against the T73 in the same stone and against the same cut in diamond.

[Get the files](https://digitalgemology.com/gemstones/tanzanite/old-mine#buy) [Open it in the Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-mine&stone=tanzanite&ct=1.00&view=angle&lighting=studio&turn=0) [All cuts in tanzanite](https://digitalgemology.com/gemstones/tanzanite)

Light Return map of the Old Mine Cut in tanzanite, face-up, from our own tracer at refractive index 1.685. Red, green and blue return light to the eye; gray leaks.

## Old Mine Cut Tanzanite

Tanzanite has a refractive index of 1.685 to 1.707 and a dispersion of 0.019. Its critical angle, from the low end of that range, is 36.4°, so a round design needs a pavilion of at least 36.4° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.696, the midpoint of the published range, and a fire spread of 0.016, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.685, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the Old Mine Cut in tanzanite live.

The Old Mine Cut has 74 facets, a table of 60.3% of its width and a total depth of 65.6% of its width; its pavilion mains sit at 44.4°. In tanzanite, the census returns 47 of 100 for brilliance and 38 for fire, against 92 and 47 for the T73, our benchmark, in the same stone; the same Old Mine Cut in diamond reads 59 and 72.

## Is tanzanite good in an Old Mine? Pros and cons, measured

### Pros

- [Lighter than the same cut in diamond](https://digitalgemology.com/gemstones/tanzanite/old-mine#pro-weight) 1.15 vs 1.21 ct

### Cons

- [Returns less light than the T73 in tanzanite](https://digitalgemology.com/gemstones/tanzanite/old-mine#con-brilliance) 47 vs 92
- [Leaks more light than the T73 in tanzanite](https://digitalgemology.com/gemstones/tanzanite/old-mine#con-leak) 52 vs 8
- [Less fire in tanzanite than in diamond](https://digitalgemology.com/gemstones/tanzanite/old-mine#con-fire) 38 vs 72
- [A less regular pavilion than the T73](https://digitalgemology.com/gemstones/tanzanite/old-mine#con-symm) 90 vs 100

Compared with the T73 Round Brilliant in tanzanite and with the Old Mine 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](https://digitalgemology.com/about/how-we-measure).

## All eight scores against the T73

At a glance: the Old Mine Cut in tanzanite (white) against the T73 Round Brilliant in tanzanite (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 tanzanite: ahead on 2, behind on 6.

- Global 61, the comparison 80, difference −19
- Brilliance 47, the comparison 92, difference −45
- Fire 38, the comparison 47, difference −9
- Scintillation 81, the comparison 80, difference +1
- Spread 98, the comparison 100, difference −2
- Symmetry 90, the comparison 100, difference −10
- Shape-norm 73, the comparison 99, difference −26
- Tilt 100, the comparison 73, difference +27

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](https://digitalgemology.com/tools/cut-performance-wheel?cut=old-mine&stone=tanzanite); these are the same census figures as our [Cut Performance Index](https://digitalgemology.com/learn/cut-performance-index).

## What the Old Mine Cut gains in tanzanite

### Lighter than the same cut in diamond

**1.15 ct** at 6.5 mm, against 1.21 ct for the same cut in diamond (−5%)

Weight follows specific gravity: 3.35 for tanzanite against 3.52 for diamond, so the same model at the same size weighs 1.15 ct here and 1.21 ct in diamond, 6.5 mm across. Nothing about the light changes with it.

*Weight of a 6.5 mm Old Mine Cut: 1.15 ct in tanzanite, 1.21 ct in diamond*

A Old Mine 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 Mine Cut page](https://digitalgemology.com/cuts/old-mine#stones)

## What the Old Mine Cut gives up in tanzanite

### Returns less light than the T73 in tanzanite

**Brilliance 47** against 92 for the T73 Round Brilliant in tanzanite: 45 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 tanzanite, whose critical angle is 36.4°, the Old Mine Cut returns 47 of 100 and the T73 92. The Old Mine Cut's pavilion mains sit at 44.4°, the T73's at 40.8°. The maps below show where each stone's light returns from and where it leaks.

Old Mine Cut in tanzanite · Brilliance 47

T73 Round Brilliant in tanzanite · Brilliance 92

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](https://digitalgemology.com/gemstones/tanzanite/dg-m5) reads 100 for brilliance in tanzanite, the best of the cuts we score there.

[Try it yourself: Open this Light Return map in the simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-mine&stone=tanzanite&ct=1.00&view=up&map=1&turn=0)

### Leaks more light than the T73 in tanzanite

**Leakage 52** against 8 for the T73 Round Brilliant in tanzanite: 44 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 Mine Cut leaks 52% in tanzanite against 8% for the T73 in tanzanite. Grey in the maps below is leaking light; the share under each picture is that picture's own.

Old Mine Cut in tanzanite · Leakage 52

0° · 54% leak

10° · 49% leak

20° · 47% leak

30° · 39% leak

T73 Round Brilliant in tanzanite · Leakage 8

0° · 9% leak

10° · 19% leak

20° · 30% leak

30° · 32% leak

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](https://digitalgemology.com/gemstones/tanzanite/dg-m5) reads 0% for leakage in tanzanite, the best of the cuts we score there.

[Try it yourself: Tilt it yourself in the simulator's light map](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-mine&stone=tanzanite&ct=1.00&view=up&map=1&turn=0)

### Less fire in tanzanite than in diamond

**Fire 38** against 72 for the Old Mine Cut in diamond: 34 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 (0.016 in tanzanite) and counts a ray as fire when the two directions differ by more than 0.6°. The Old Mine Cut reads 38 against 72 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders tanzanite'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](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-mine&stone=tanzanite&ct=1.00&view=up&lighting=sun&turn=0): the Old Mine Cut in tanzanite under the sunny-day lighting.

**What helps:** [the DG-Elongated Hexagon](https://digitalgemology.com/gemstones/tanzanite/dg-elongated-hexagon) reads 79 for fire in tanzanite, the best of the cuts we score there.

[Try it yourself: See the fire in the 3D Gemstone Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-mine&stone=tanzanite&ct=1.00&view=up&lighting=sun&turn=0)

### A less regular pavilion than the T73

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

Symmetry reads how evenly the pavilion facets of each design family are cut: 100 − 6 × their scatter in degrees. The Old Mine Cut reads 90, the T73 100. It depends on the geometry alone, so it is the same in every stone.

*Facet diagram of the Old Mine Cut: its pavilion, seen from below, 74 facets in all*

Old Mine Cut · 74 facets · Symmetry 90

*Facet diagram of the T73 Round Brilliant: its pavilion, seen from below, 73 facets in all*

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.

[Try it yourself: Compare the Symmetry spoke in the Cut Performance Wheel](https://digitalgemology.com/tools/cut-performance-wheel?cut=old-mine&stone=tanzanite)

## Our verdict on the Old Mine Cut in tanzanite

Pick the Old Mine Cut in tanzanite for this: it weighs less than in diamond. The catch: it returns less light than the T73, leaks more light than the T73, shows less fire than in diamond and has a less regular pavilion than the T73.

If that catch matters more to you, [the DG-M5](https://digitalgemology.com/gemstones/tanzanite/dg-m5) reads 100 for brilliance in tanzanite, 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 Mine Cut model we traced.

## Old Mine Cut Tanzanite: questions

### Is the Old Mine a good cut for tanzanite?

In our census the Old Mine Cut returns 47 of 100 for brilliance and 38 for fire in tanzanite, against 92 and 47 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 tanzanite need?

At least 36.4° for a round design: tanzanite's critical angle is 36.4°, 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 Mine Cut's pavilion mains sit at 44.4°.

### How much does a Old Mine weigh in tanzanite?

At 6.5 mm across, 1.15 ct in tanzanite, against 1.21 ct for the same cut in diamond (-5%): tanzanite's specific gravity is 3.35, diamond's 3.52.

### Can I see the Old Mine in tanzanite in 3D?

Yes: the 3D Gemstone Simulator renders it live, with tanzanite's own refractive index and dispersion. Tanzanite 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 Mine Cut files

*6 formats* *Millimeters* *Watertight*

### 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.

- **STEP** Exact faceted solid for CAD
- **3DM** Rhino, closed mesh on its own layer
- **STL** Watertight mesh for printing and casting
- **OBJ** Mesh for modeling and rendering
- **FBX** Blender, 3ds Max, Maya, Cinema 4D, Unity, Unreal
- **GLB** Web, AR and quick previews

€9.99 · [Personal use](https://digitalgemology.com/licence) [Buy the 3D files](https://digitalgemology.lemonsqueezy.com/checkout/buy/5b3b75f2-db63-4e1c-8acc-ed119e91984a)

*GemCad* *96 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.

- **.asc** GemCad design file, 96 index gear
- **.csv** Tier table: angles, indices and cutting order
- **Diagram** Printable faceting diagram

€6.99 · [Personal use](https://digitalgemology.com/licence) [Buy the cutting files](https://digitalgemology.lemonsqueezy.com/checkout/buy/54ae00b8-0467-47be-a84f-354652bd5c37)

Save with a bundle: the Old Mine Cut 3D and cutting files are also in [Historic Cuts Complete](https://digitalgemology.com/cuts/#bundles), 6 cuts for €29.99 until 1 December, then €39.99 (€101.88 as single files). [Buy the bundle](https://digitalgemology.lemonsqueezy.com/checkout/buy/dcf2c236-6e04-4292-8040-9d21ac6446d1?checkout%5Bdiscount_code%5D=HISTORIC25).

Not sure the files open in your software? [Get the cube free](https://digitalgemology.lemonsqueezy.com/checkout/buy/2d1ab55f-2bd6-4897-a4cd-f3320f54e99e): the same six formats, for your email address, used only to send them ([privacy](https://digitalgemology.com/privacy#free-sample)).

Questions before you buy? [Email us](mailto:support@digitalgemology.com).

## More gemstones and cuts

[Tanzanite: optical properties and the top ten cuts](https://digitalgemology.com/gemstones/tanzanite) · [The Old Mine Cut: specifications, model and files](https://digitalgemology.com/cuts/old-mine)

### Other cuts in tanzanite

- [T73 Round Brilliant](https://digitalgemology.com/gemstones/tanzanite/t73-round-brilliant)
- [T105 Round Brilliant](https://digitalgemology.com/gemstones/tanzanite/t105-round-brilliant)
- [DG-Vitruvio](https://digitalgemology.com/gemstones/tanzanite/dg-vitruvio)
- [DG-Anteros](https://digitalgemology.com/gemstones/tanzanite/dg-anteros)
- [DG-Broken Hearts and Arrows](https://digitalgemology.com/gemstones/tanzanite/dg-broken-hearts-and-arrows)
- [Baguette Cut](https://digitalgemology.com/gemstones/tanzanite/baguette)
- [Emerald Cut](https://digitalgemology.com/gemstones/tanzanite/emerald-cut)
- [Marquise Cut](https://digitalgemology.com/gemstones/tanzanite/marquise)
- [Oval Cut](https://digitalgemology.com/gemstones/tanzanite/oval)
- [Pear Cut](https://digitalgemology.com/gemstones/tanzanite/pear)
- [Radiant Cut](https://digitalgemology.com/gemstones/tanzanite/radiant)
- [Rectangle Cut](https://digitalgemology.com/gemstones/tanzanite/rectangle)
- [Teardrop Cut](https://digitalgemology.com/gemstones/tanzanite/teardrop)
- [Asscher Cut](https://digitalgemology.com/gemstones/tanzanite/asscher)
- [Cushion Cut](https://digitalgemology.com/gemstones/tanzanite/cushion)
- [Emerald Square Cut](https://digitalgemology.com/gemstones/tanzanite/emerald-square)
- [Princess Cut](https://digitalgemology.com/gemstones/tanzanite/princess)
- [Radiant Square Cut](https://digitalgemology.com/gemstones/tanzanite/radiant-square)
- [Square Cut](https://digitalgemology.com/gemstones/tanzanite/square)
- [Triangle Cut](https://digitalgemology.com/gemstones/tanzanite/triangle)
- [Trilliant Cut](https://digitalgemology.com/gemstones/tanzanite/trilliant)
- [Trillion Cut](https://digitalgemology.com/gemstones/tanzanite/trillion)
- [Hexagon Cut](https://digitalgemology.com/gemstones/tanzanite/hexagon)
- [Octagon Cut](https://digitalgemology.com/gemstones/tanzanite/octagon)
- [Portuguese Bird's Nest Cut](https://digitalgemology.com/gemstones/tanzanite/portuguese-birds-nest)
- [Old Single Cut](https://digitalgemology.com/gemstones/tanzanite/old-single)
- [Mazarin Cut](https://digitalgemology.com/gemstones/tanzanite/mazarin)
- [Peruzzi Cut](https://digitalgemology.com/gemstones/tanzanite/peruzzi)
- [Old European Cut](https://digitalgemology.com/gemstones/tanzanite/old-european)
- [T57 Round Brilliant](https://digitalgemology.com/gemstones/tanzanite/t57-round-brilliant)
- [DG-M5](https://digitalgemology.com/gemstones/tanzanite/dg-m5)
- [DG-Miliano](https://digitalgemology.com/gemstones/tanzanite/dg-miliano)
- [DG-Rafaello](https://digitalgemology.com/gemstones/tanzanite/dg-rafaello)
- [DG-Bowtie](https://digitalgemology.com/gemstones/tanzanite/dg-bowtie)
- [DG-Elongated Hexagon](https://digitalgemology.com/gemstones/tanzanite/dg-elongated-hexagon)
- [DG-Octagonal Kite](https://digitalgemology.com/gemstones/tanzanite/dg-octagonal-kite)

### The Old Mine Cut in other gemstones

- [Diamond](https://digitalgemology.com/gemstones/diamond/old-mine)
- [Moissanite](https://digitalgemology.com/gemstones/moissanite/old-mine)
- [Cubic Zirconia](https://digitalgemology.com/gemstones/cubic-zirconia/old-mine)
- [Sapphire](https://digitalgemology.com/gemstones/sapphire/old-mine)
- [Ruby](https://digitalgemology.com/gemstones/ruby/old-mine)
- [Emerald](https://digitalgemology.com/gemstones/emerald/old-mine)
- [Amethyst](https://digitalgemology.com/gemstones/amethyst/old-mine)
- [Topaz](https://digitalgemology.com/gemstones/topaz/old-mine)
- [Spinel](https://digitalgemology.com/gemstones/spinel/old-mine)
- [Demantoid](https://digitalgemology.com/gemstones/demantoid/old-mine)
- [Zircon](https://digitalgemology.com/gemstones/zircon/old-mine)
- [Tourmaline](https://digitalgemology.com/gemstones/tourmaline/old-mine)
- [Peridot](https://digitalgemology.com/gemstones/peridot/old-mine)
- [YAG](https://digitalgemology.com/gemstones/yag/old-mine)
- [Pyrope](https://digitalgemology.com/gemstones/pyrope/old-mine)
- [Almandine](https://digitalgemology.com/gemstones/almandine/old-mine)
- [Spessartine](https://digitalgemology.com/gemstones/spessartine/old-mine)
- [Grossular](https://digitalgemology.com/gemstones/grossular/old-mine)
- [Chrysoberyl](https://digitalgemology.com/gemstones/chrysoberyl/old-mine)
- [Kunzite](https://digitalgemology.com/gemstones/kunzite/old-mine)
- [Iolite](https://digitalgemology.com/gemstones/iolite/old-mine)
- [Morganite](https://digitalgemology.com/gemstones/morganite/old-mine)
- [GGG](https://digitalgemology.com/gemstones/ggg/old-mine)
- [Strontium titanate](https://digitalgemology.com/gemstones/strontium-titanate/old-mine)
- [Synthetic rutile](https://digitalgemology.com/gemstones/synthetic-rutile/old-mine)