11.78ct Chrome Tourmaline rough, table view

11.78ct Chrome Tourmaline rough, pavilion view

11.78CT Chrome Tourmaline Faceting Rough | Uncut Gemstone

Name: 11.78CT Chrome Tourmaline Faceting Rough
Brand: Jackson's Gems
SKU: wj-C-Ow8wz4
Price: 1178.00 USD
Availability: InStock

$1,178.00

Green 11.78CT Chrome Tourmaline Rough from Tanzania. Eye clean clarity, 16.79×12.40×8.34mm size. Best suited for oval, pear, or emerald shapes.

1 in stock

SKU: wj-C-Ow8wz4 Categories: Tourmaline, Chrome Tourmaline

Technical Specifications & Gemological Properties

Specifications for 11.78CT Chrome Tourmaline Faceting Rough
Carat Weight	11.78CT
Dimensions	16.79 × 12.40 × 8.34mm
Origin	Tanzania
Treatment	None known
Color	Green
Clarity Grade	Eye Clean
Gem family	Tourmaline
Variety	Chrome Tourmaline
Recommended shapes	Oval, Pear, Emerald
Refractive Index	1.62–1.64 ^†
Hardness (Mohs)	7–7.5 ^†
Optic Character	Doubly refractive, uniaxial (−), birefringence 0.018–0.020 ^†
Pleochroism	Moderate to strong (dichroic) ^†
Specific Gravity	3.02–3.26 ^†

† Typical reference value for tourmaline; individual stones vary.

How to orient and cut this rough — Lapidary Guide

Description

Eye clean clarity allows for high transparency in this 11.78CT Chrome Tourmaline Rough. This facet rough shows a saturated green color that varies in tone based on the view angle. The stone comes from Tanzania and measures 16.79×12.40×8.34mm. An oval, pear, or emerald shape fits these dimensions well to maximize the material.

11.78CT Chrome Tourmaline Rough Specifications

Lapidary notes: Clean rough; Open C-axis

Cutting Notes

Orient the table across the C-axis to achieve a lighter green tone. This rough is clean and the C-axis is open, which simplifies the preforming process. The dimensions support a long oval or a pear shape. An emerald cut also works well with the current proportions of the rough.

Keep the stone cool during the grinding process because Chrome Tourmaline is heat sensitive. Use light pressure to avoid fractures since the material is brittle. The refractive index is high, so you may see doubled facet edges. Set pavilion angles above 38 degrees to prevent windowing and light leakage.

Cutter’s tip: Use a slow wheel speed during the final polish to prevent heat buildup in the brittle material.

Every stone is filmed on video before it is listed, so what you see is the stone you get. For background on Chrome Tourmaline, see the GIA Tourmaline guide. Browse more Chrome Tourmaline faceting rough from Jackson’s Gems.

Related Guides

New to cutting Tourmaline? See the Lapidary Guide.

Questions About This Chrome Tourmaline Rough

How does the C-axis affect the color of Chrome Tourmaline?

The color often looks darker when you look down the C-axis. Cutters usually place the table across the axis for lighter tones or parallel to it for darker tones.

What is the critical angle for this material?

The critical angle is about 38 degrees. You must cut the pavilion angles above this limit to avoid a window in the finished gem.

Is this material prone to fracturing during faceting?

Yes, Chrome Tourmaline is brittle and sensitive to heat. You should use a cool lubricant and avoid heavy pressure on the lap.

Why do some facet edges look doubled in this stone?

This occurs because the material has a high birefringence of 0.018 to 0.020. This optical property causes the light to split into two rays.

What is the typical hardness of Chrome Tourmaline?

It has a Mohs hardness of 7 to 7.5. This makes it durable for wear but requires a steady hand during the polishing stage.

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