BOU008 · synthetic lapidary teaching lab
Explore how orientation, retained host rock, illustrative cutting paths and structural boundaries can create competing preservation choices. Every rough shape and outcome here is authored for teaching: it is not a real specimen and it is not cutting advice for an actual stone.
SIMULATION · NOT A REAL SPECIMEN
Choose among three kinds of decisions, then compare deterministic consequences inside this synthetic fixture. Nothing is measured from a photograph or user-owned stone.
SIMULATION · BOU008-SIM-ROUGH-A · NOT A REAL SPECIMEN · NOT CUTTING ADVICE FOR AN ACTUAL STONE
The diagram deliberately omits workshop procedure and machine settings. It does not provide blade, grit, speed, pressure, coolant, PPE or operational safety instructions.
No-JavaScript lapidary guide
These cards separate published cutting context from BOU-authored mechanics. External source images are not reproduced.
Geoscience Australia describes Queensland boulder opal in ironstone veins/centre fillings, with opal-indicated boulders sliced to expose veins and precious-bearing slices blocked out before specialist cutting and polishing.
High-level processing context only. This page does not tell you where to saw a real stone.
The Australian Museum describes boulder opal as a thin precious layer indivisible from ironstone matrix and notes that boulder-opal shapes can follow natural undulations.
This supports host-retention as a teaching concept, not a prescribed amount of matrix for a real specimen.
GIA states that opal cutters consider color, pattern and clarity, and that fine opal can be fashioned in irregular shapes to retain and display play-of-color.
The simulation translates that broad idea into synthetic trade-offs; it does not calculate value or an optimum.
A GIA case study of a large South Australian opal documents studying color bars, potch and fractures and considering which side should become the top before a major cut.
This is one non-boulder-opal case study. BOU uses it only to explain why viewing-face choice appears in the simulation.
No-JavaScript simulation explanation
The table below is the complete authored outcome matrix. “Material retained” is a low/medium/high fixture label, not a mass, carat-yield prediction, value estimate or recommended cut.
| Face | Host choice | Path | Seam exposure | Synthetic material retained | Host retained | Marked boundary interaction |
|---|---|---|---|---|---|---|
| face-a | retain | contour | high | high | high | approaches one marked boundary |
| face-a | retain | window | high | medium | high | crosses one marked boundary |
| face-a | retain | perimeter | medium | high | high | stays outside the marked boundary |
| face-a | trim | contour | high | low | low | approaches one marked boundary |
| face-a | trim | window | high | low | low | crosses one marked boundary |
| face-a | trim | perimeter | high | medium | low | stays outside the marked boundary |
| face-b | retain | contour | high | high | high | approaches one marked boundary |
| face-b | retain | window | high | medium | high | crosses one marked boundary |
| face-b | retain | perimeter | low | high | high | stays outside the marked boundary |
| face-b | trim | contour | high | low | low | approaches one marked boundary |
| face-b | trim | window | high | low | low | crosses one marked boundary |
| face-b | trim | perimeter | medium | medium | low | stays outside the marked boundary |
Decision vocabulary
These are educational abstractions for BOU008-SIM-ROUGH-A. They are not diagnostic categories for a stone on your bench.
Face A exposes more of the authored seam; Face B leaves more host visually dominant. This is a deterministic visual arrangement, not analysis.
The choice illustrates that host rock can be materially and visually connected to boulder opal. It does not prescribe how much ironstone a real cutter should keep.
The three drawn paths interact differently with one marked synthetic boundary. Their consequences are hard-coded to the teaching fixture.
Low/medium/high describes only the amount of synthetic diagram material left by the authored scenario. It never predicts carats, recovery, price, rarity or quality.
Evidence bridges
The Lab explains generic anatomy, Formation explains broad geology, and the Cabinet preserves documented specimen evidence. The links below do not imply those source specimens were cut in any particular way.
Lapidary context
The existing synthetic rough is useful for discussing viewing face, host retention and hidden structure. It never predicts yield, optimum cut, rarity, authenticity or price for a real stone.
Real material requires hands-on judgment. When irreversible cutting decisions matter, use an experienced lapidary who can inspect the actual material.
ICU / CONNECTED DISCOVERY
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