cut-gemstone

name	cut-gemstone
locale	wenyan-ultra
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"}

切寶石

自原以雞心與刻面法切寶石，含原評、向計、膠、磨、刻面幾。

用

• 有原欲切為畢雞心或刻面石
• 需計切向為佳色、產、光象
• 首設雞心或刻面機
• 欲曉標亮切冠與底角
• 需為材擇合切法

入

• 必：原寶石（已識種——見 identify-gemstone）
• 必：切法決：雞心或刻面
• 必：目形與約寸
• 可：鑽刃修鋸
• 可：80/220/600/1200/3000 目輪之雞心機
• 可：含索齒、桅、盤之刻面機
• 可：膠蠟或環氧、膠棒、酒精燈
• 可：標校寸（橢、圓、馬眼）模

行

一：原評與安察

切前評原材。

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.

1. 確種識（疑則先行 identify-gemstone）
2. 察毒塵險——某材需額外防
3. 強透光下察裂
4. 映色區與內含位
5. 估原可生之畢形

得： 原評備含種確、裂映、色識、切謀成。

敗： 原廣裂→考可穩（多孔材環氧浸）或產過低不值切。某原勝售或換為標本材。

二：向計

定色與象之最佳切向。

Orientation Principles by Stone Type:

PLEOCHROIC STONES (tourmaline, sapphire, tanzanite, iolite):
- Orient the table perpendicular to the crystal axis showing
  the best face-up colour
- Tourmaline: the c-axis often shows dark/opaque colour —
  orient the table to view the a/b axis colour
- Sapphire: slight pleochroism — orient for deepest blue face-up
- Tanzanite: trichroic — blue/violet axis preferred for table

STAR STONES (star ruby, star sapphire):
- Silk (rutile needles) must be parallel to the base
- Cut as cabochon with the dome centred over the silk
- The star appears at 90 degrees to the silk orientation

CAT'S EYE STONES (chrysoberyl cat's eye, tiger's eye):
- Fibrous inclusions must run perpendicular to the length
  of an elongated cabochon
- The eye appears as a bright line across the shortest dimension

COLOUR-ZONED MATERIAL (sapphire, ametrine, watermelon tourmaline):
- Position colour zones so they are not visible face-up
- Or feature them intentionally (ametrine, watermelon tourmaline)

1. 定石含多色否——自多向以二色鏡察
2. 象石（星、貓眼）—尋含模向
3. 色區材——決隱或顯區
4. 以鋁筆於原標向
5. 計檯位與深為擇向最大產

得： 含標檯向、向、約輪之原石。切謀優色現與產。

敗： 最佳色向衝最大產→按優先決：色質幾恆增值勝加克重。疑則向色。

三：雞心切

於雞心機塑石為凸雞心。

Cabochon Cutting Sequence:

EQUIPMENT SETUP:
- Cabbing machine with water drip on all wheels
- Wheel sequence: 80, 220, 600, 1200, 3000 (or 1200 + polish)
- Dop sticks and dop wax (or cyanoacrylate adhesive)
- Safety glasses — MANDATORY
- Avoid loose clothing, tie back long hair

STEP-BY-STEP:
1. SLAB: Cut a slab 5-8mm thick through the best area
2. TEMPLATE: Mark the desired outline (oval, round, etc.)
   using a template and aluminum pencil
3. TRIM: Remove excess material on the trim saw or 80-grit wheel
   Cut close to the line but leave 1-2mm margin
4. DOP: Attach the slab to a dop stick with dop wax
   Heat the wax, press the stone flat-side down, centre it
5. SHAPE (80 grit): Grind to the template outline
   Work all the way around, maintaining symmetry
6. DOME (220 grit): Shape the dome profile
   Standard dome height = ~1/3 of the stone's width
   Keep the dome symmetrical — check from all angles
7. SMOOTH (600 grit): Remove 220-grit scratches
   Work systematically, keeping even pressure
8. PRE-POLISH (1200 grit): Remove 600-grit scratches
   The surface should feel smooth to the fingernail
9. FLAT BOTTOM: Remove the stone from the dop, re-dop
   face-down, and grind the bottom flat on 220 → 600 grit
10. POLISH: See polish-gemstone skill for final finishing

1. 設雞心機含諸輪水流
2. 戴安鏡——無例
3. 切板而標模輪
4. 穩膠石——磨中松石險
5. 80 目磨形、220 凸、600 至 1200 平
6. 保凸續均勻——凸不均於磨後現「平點」

得： 勻凸雞心備為終磨、含稱輪、均凸高、無 1200 目階之見痕。

敗： 凸含平點或不稱→返 220 目再塑。失少材勝磨不均凸。石磨中離膠→慎重膠續——先察石為缺。

四：刻面

以刻面機切精幾面。

Standard Round Brilliant Angles (quartz-family, RI ~1.54):
+------------------+-------+--------+
| Facet            | Angle | Index  |
+------------------+-------+--------+
| Crown main       | 42°   | 96-index: 3,9,15,21,27,33,39,45 |
| Crown break      | 25°   | (bisect mains)                   |
| Crown star       | 15°   | (bisect breaks toward table)     |
| Table            | 0°    | flat    |
| Pavilion main    | 43°   | 96-index: 3,9,15,21,27,33,39,45 |
| Pavilion break   | Use GemCad or published diagrams           |
+------------------+-------+--------+

Standard Round Brilliant Angles (corundum, RI ~1.76):
+------------------+-------+
| Facet            | Angle |
+------------------+-------+
| Crown main       | 37°   |
| Pavilion main    | 41°   |
+------------------+-------+

CRITICAL: Pavilion angles determine brilliance.
- Too shallow → light leaks through bottom ("windowing")
- Too steep → dark extinction zones
- Correct angle → total internal reflection (brilliance)

1. 為目形與材 RI 擇刊刻面圖
2. 備原：平底側（尖底朝下）
3. 膠石——圓石用錐膠、他用平膠
4. 粗盤（600 目鑽）先以刊角切底面
5. 諸底面至精點（「底尖會」）
6. 轉至錐膠（或用轉夾）切冠
7. 先冠主、後破、後星、終立檯
8. 各層預磨與磨（見 polish-gemstone 擇盤與複合）

得： 刻面石含精會（面緣合於單點）、一致面寸、善稱、材 RI 合角。

敗： 會偏→角或索設略誤。復察刊圖。「追會」（調一面修他）積誤——誤大時勝重切層。小會誤初者常、不顯影光。

五：切後察

終磨前評切石。

1. 徹淨石
2. 察稱：上觀（輪）、側觀（比）、透檯觀（會精）
3. 雞心：驗凸均、察平點、確輪形一致
4. 刻面：10x 鏡下察會、察切階餘面痕
5. 量終寸與重
6. 見缺→磨前返合切步

得： 全切石合稱、會、面備之質準、備為磨階。

敗： 顯缺見（稱差、會差、比誤）→現重切勝磨缺石後重切。記誤為下石。

驗

• 切前種識且毒塵險評
• 安具全戴（眼護、塵/濺控）
• 諸磨切操水冷活
• 向為佳色或象計
• 雞心凸稱無平點（雞心路）
• 面會合於點無顯偏（刻面路）
• 終寸量錄
• 石無切階痕、備為磨

忌

• 切無識石：某材生毒塵（孔雀石、朱砂、石棉）。切前恆識。恆水冷
• 略向計：多色石不向色致畢寶暗或誤色、本可正向得美
• 乾磨：乾磨生矽塵（慢健險）且熱石（熱震或裂）。諸輪盤水續流
• 躍階：躍 220 至 1200 目遺深痕磨後現。各目階須全除前階痕
• 膠敗：膠黏不足石磨中移或飛。用足蠟、保石暖（非冷）、膠涼盡方磨

參

• identify-gemstone — 切前須種識
• polish-gemstone — 切後次步，含盤擇、複合擇、終磨