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name: cut-gemstone locale: wenyan-lite source_locale: en source_commit: 82c77053 fence_basis_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

自原料以凸圓面與刻面之技切寶石，涵原料評、方位規劃、固夾、研磨、刻面幾何。

適用時機

• 有原寶石料欲切為凸圓面或刻面之成石
• 須規劃切向以得最優之色、產率、或光現象
• 初立凸圓機或刻面機時
• 欲明標準圓明亮切之冠與亭角
• 為特料擇合宜之切法

輸入

• 必要：原寶石料（已辨種——見 identify-gemstone）
• 必要：切法決定：凸圓面或刻面
• 必要：目標形與約大小
• 選擇性：含鑽鋸片之修鋸
• 選擇性：含 80/220/600/1200/3000 目輪之凸圓機（供凸圓面）
• 選擇性：含索引齒、桅桿、盤組之刻面機（供刻面）
• 選擇性：固夾蠟或環氧、固夾棒、酒精燈
• 選擇性：標準校尺之範本（橢、圓、馬眼）

步驟

步驟一：原料評與安全察

切前先評原料。

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. 確認種之辨識（疑則先行 identify-gemstone）
2. 察毒塵風險——某料需額外防護
3. 於強透光下察裂
4. 映色區與含物位
5. 估原料可出之成形

預期： 有錄之原料評，種已確、裂已映、色區已辨、切計畫已成。

失敗時： 若原料裂廣，考慮其可穩否（多孔料之環氧浸）或產率是否過低不值切。某原料較宜售或交換為標本料。

步驟二：方位規劃

定最佳切向以得色與現象。

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. 定石是否多色——自多向透二色鏡察
2. 對現象石（星、貓眼），定含物模式並依之方位
3. 對色區料，決藏或顯色區
4. 以鋁筆於原料上標方位
5. 計台位與深以於所擇方位最大化產率

預期： 已標原石含台向、方位、約輪廓。切計畫優化色呈現與產率。

失敗時： 若最佳色向與最大產率衝，按優先度決：色質幾恒增值勝過加克拉重。疑則為色定向。

步驟三：凸圓切

於凸圓機上將寶石塑為圓頂之凸圓面。

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. 立凸圓機，所有輪皆水流
2. 戴安全眼鏡——無例外
3. 切板並標範本輪廓
4. 穩固夾石——研磨中鬆石危險
5. 於 80 目成形、於 220 圓頂、經 600 與 1200 平滑
6. 全程保一致之圓頂曲度——不均之頂於拋光後顯「平點」

預期： 平滑圓頂之凸圓面，備供終拋光，輪廓對稱、頂均、1200 目階之痕不見。

失敗時： 若頂有平點或不對稱，返 220 目重塑。寧失少料於拋光不均之頂。若研磨時石脫固夾，慎重固之並續——先察石是否有缺角。

步驟四：刻面

以刻面機切精確之幾何面。

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. 擇合目標形與料 RI 之已刊刻面圖
2. 備原料：平亭面側（尖底將朝下）
3. 固夾石——圓石用圓錐固夾、他用平固夾
4. 先於粗盤（600 目鑽）按已刊角切亭面
5. 令所有亭面會於一精確點（「底尖會合」）
6. 換圓錐固夾（或用轉移夾具）以切冠
7. 切冠主面、繼破面、繼星面，末立台面
8. 各層預拋與拋（見 polish-gemstone 以擇盤與化合物）

預期： 刻面寶石含精會（面邊會於一點）、一致之面尺、良對稱、合料 RI 之角。

失敗時： 若面會偏，角或索引設略誤。重察已刊圖。「追會合」（調一面以修他）積誤——若誤大，寧重切該層。初學之小會合誤為常，不顯著影響光輝。

步驟五：切後察

至終拋光前評已切之石。

1. 徹清石
2. 察對稱：自上察（輪廓）、自側察（比）、經台察（會合精度）
3. 凸圓面：驗頂均、察平點、確保輪廓一致
4. 刻面石：於 10x 放大鏡下察會合、尋切階殘痕
5. 量終尺寸與重
6. 若尋缺，於拋光前返相應切步

預期： 全切之石合對稱、會合、表面備之品質標準，備至拋光階段。

失敗時： 若尋顯著缺（對稱差、會合差、比誤），今重切較後拋光之缺石重切更省時。記何誤以供次石。

驗證

• 切前種已辨且毒塵風險已評
• 全程戴安全具（眼護、塵/濺控）
• 所有研磨與切作皆水冷激活
• 方位已計以最優色或現象
• 凸圓面之頂對稱且無平點（凸圓路）
• 刻面會於點而無顯著偏移（刻面路）
• 終尺寸已量並錄
• 石無切階之痕，備拋光

常見陷阱

• 切未辨之石：某料產毒塵（孔雀石、辰砂、溫石綿）。切前恒辨之。恒用水冷無論
• 跳方位規劃：不為色定向而切多色石可生當以正方位可美之鈍或失色之成石
• 乾磨：乾磨產矽塵（慢性健康險）且過熱石（熱衝可致裂）。水須於所有輪與盤持流
• 疾過目：自 220 跳至 1200 目留深痕於拋光後顯。各目階須全除前階之痕
• 固夾敗：固夾附不足致石於研磨中移或飛脫。用足蠟、確保石溫（非冷）、令固夾全冷方研

相關技能

• identify-gemstone —— 切始前需種辨識
• polish-gemstone —— 切後之次步，涵盤擇、化合物擇、終光