cut-gemstone

name	cut-gemstone
locale	caveman
source_locale	en
source_commit	82c77053
translator	Julius Brussee homage — caveman
translation_date	2026-04-19
description	Cut gemstones using cabochon and faceting techniques. Covers rough assessment, orientation for optimal color and yield, dopping, cutting angles, and crown/pavilion geometry for standard brilliant cuts. Use when you have rough gemstone material to cut into a cabochon or faceted stone, planning cutting orientation for optimal colour or optical phenomena, setting up a cabbing or faceting machine, or selecting the appropriate cutting approach for a given material.
license	MIT
allowed-tools	Read
metadata	{"author":"Philipp Thoss","version":"1.0","domain":"lapidary","complexity":"advanced","language":"natural","tags":"lapidary, cutting, faceting, cabochon, gemstones"}

Cut Gemstone

Cut gemstones from rough material. Cabochon and faceting techniques. Rough assessment, orientation planning, dopping, grinding, faceting geometry.

When Use

• Have rough gemstone material. Want to cut into finished cabochon or faceted stone
• Need to plan cutting orientation for optimal colour, yield, optical phenomena
• Setting up cabbing machine or faceting machine for first time
• Want to understand crown and pavilion angles for standard brilliant cuts
• Need to pick right cutting approach for given material

Inputs

• Required: Rough gemstone material (identified species — see identify-gemstone)
• Required: Cutting approach decision: cabochon or faceting
• Required: Target shape and approximate size
• Optional: Trim saw with diamond blade
• Optional: Cabbing machine with 80/220/600/1200/3000 grit wheels (for cabochons)
• Optional: Faceting machine with index gear, mast, and lap set (for faceting)
• Optional: Dop wax or epoxy, dop sticks, alcohol lamp
• Optional: Templates (oval, round, marquise) in standard calibrated sizes

Steps

Step 1: Rough Assessment and Safety Check

Evaluate rough material before any cutting begins.

Rough Assessment Checklist:
+--------------------+------------------------------------------+
| Factor             | Assessment                               |
+--------------------+------------------------------------------+
| Species            | Identified? (MANDATORY before cutting)   |
|                    | Toxic dust risk? (check below)           |
+--------------------+------------------------------------------+
| Fractures          | Internal fractures that limit yield?     |
|                    | Will the stone break during cutting?     |
+--------------------+------------------------------------------+
| Colour zones       | Where is the best colour concentrated?   |
|                    | Can the cut centre the colour?           |
+--------------------+------------------------------------------+
| Inclusions         | Large inclusions that should be cut away?|
|                    | Silk for star stones? (orient for star)  |
+--------------------+------------------------------------------+
| Size and shape     | What finished shapes fit this rough?     |
|                    | Calibrated size possible?                |
+--------------------+------------------------------------------+
| Yield estimate     | Approximate finished weight as % of rough|
|                    | Typical: 25-40% for faceting             |
|                    | Typical: 40-60% for cabochons            |
+--------------------+------------------------------------------+

SAFETY — TOXIC DUST MATERIALS:
These minerals produce hazardous dust when cut. Use wet cutting ONLY,
ensure ventilation, and wear an appropriate respirator:
- Chrysotile (asbestos serpentine) — NEVER cut dry
- Malachite — copper carbonate dust is toxic
- Cinnabar — mercury sulfide, extremely toxic
- Orpiment/Realgar — arsenic compounds
- Chrysocolla — copper silicate, moderate risk
- Tiger's eye (fibrous) — fine silica fibers

ALL stone cutting produces silica dust. Always use water cooling
and never grind or cut dry without a dust extraction system.