Polishing Compound Guide:
+-------------------+------------------------------------------+
| Compound | Best For |
+-------------------+------------------------------------------+
| Cerium oxide | Quartz family (agate, jasper, amethyst, |
| | chalcedony), feldspar, obsidian |
| | Mix: paste consistency with water |
| | Lap/pad: leather, felt, or Batt |
+-------------------+------------------------------------------+
| Diamond paste | Universal — works on everything |
| (50,000 mesh / | Essential for corundum, spinel, topaz, |
| 0.25-0.5 micron) | garnet, and other hard stones |
| | Lap: tin, copper, ceramic, Corian |
+-------------------+------------------------------------------+
| Aluminum oxide | Corundum (ruby, sapphire), spinel, |
| (0.3 micron) | chrysoberyl |
| | Lap: ceramic, tin, wax |
+-------------------+------------------------------------------+
| Tin oxide | Quartz varieties, opal (gentle polish) |
| | Lap: leather, felt, Lucite |
+-------------------+------------------------------------------+
| Chromium oxide | Jade (jadeite, nephrite), emerald |
| (green compound) | Lap: leather |
+-------------------+------------------------------------------+
| Linde A | Corundum, spinel — traditional choice |
| (aluminum oxide) | Lap: wax, ceramic, tin |
+-------------------+------------------------------------------+
Polishing Lap Guide (Faceted Stones):
+-------------------+------------------------------------------+
| Lap Material | Use |
+-------------------+------------------------------------------+
| Tin (type metal) | General-purpose polish lap. Good for |
| | most stones with diamond or alumina |
+-------------------+------------------------------------------+
| Copper | Diamond polish for hard stones |
| | (corundum, spinel, topaz) |
+-------------------+------------------------------------------+
| Ceramic (BATT, | Diamond polish. Forgiving, good for |
| Darkside, Last | beginners. Works on most materials |
| Lap) | |
+-------------------+------------------------------------------+
| Corian (solid | Oxide polishes. Good for quartz family |
| surface) | |
+-------------------+------------------------------------------+
| Lucite/Plexiglass | Oxide polish for quartz, softer stones |
+-------------------+------------------------------------------+
| Leather/felt | Cabochon polishing. Cerium oxide or |
| | tin oxide |
+-------------------+------------------------------------------+
Polishing Technique:
CABOCHON POLISHING:
1. Apply compound to the leather/felt wheel
2. Run the wheel at moderate speed (lower than grinding)
3. Hold the stone lightly — REDUCE pressure compared to grinding
4. Move the stone across the wheel surface with gentle sweeping motion
5. Polish for 2-5 minutes, checking progress with a loupe
6. Add compound sparingly — too much creates orange peel
FACETED STONE POLISHING:
1. Charge the polishing lap with compound
2. Set the SAME angle as the cutting stage for each facet tier
3. Lower the stone gently onto the spinning lap
4. Polish each facet with light, consistent pressure
5. Check each facet under a loupe before moving to the next
6. Re-charge the lap periodically but do not over-charge
SPEED AND PRESSURE:
- Polishing speed: 50-75% of cutting speed
- Pressure: LIGHT — let the compound do the work
- Heavy pressure causes heat, orange peel, and facet rounding
- On faceted stones, heavy pressure rounds facet edges ("soft meets")
Final Quality Checklist:
+--------------------+------------------------------------------+
| Criterion | Standard |
+--------------------+------------------------------------------+
| Lustre | Full, even lustre across all surfaces |
| | No dull patches or haze |
+--------------------+------------------------------------------+
| Scratches | None visible under 10x magnification |
| | Check under multiple light angles |
+--------------------+------------------------------------------+
| Orange peel | None — surface should be optically flat |
| | on each facet / smoothly curved on cabs |
+--------------------+------------------------------------------+
| Facet edges | Sharp and well-defined (faceted stones) |
| (faceted) | No rounding or "soft meets" |
+--------------------+------------------------------------------+
| Dome uniformity | Smooth, even curvature (cabochons) |
| (cabochons) | No flat spots or high points |
+--------------------+------------------------------------------+
| Cleanliness | All compound residue removed |
| | Stone cleaned ultrasonically or by hand |
+--------------------+------------------------------------------+