How to Make a Cabochon

A cabochon (pronounced cab-uh-shon) is a gemstone that has been shaped and polished with a smooth, domed top and a flat bottom, rather than being faceted with flat, angled surfaces. This traditional cut, derived from the French word for "head," highlights a stone's color, luster, and optical effects like star-shapes (asterism) or cat's-eye shimmer (chatoyancy) in opaque or translucent gems like opal, turquoise, and moonstone.  

Making a cabochon involves grinding and polishing a stone into a smooth, rounded gem with a flat back, using a series of progressively finer grit wheels or laps, starting with coarse 80-grit to shape the stone and create the dome, then moving through finer grits (like 220, 600) to remove scratches, and finally polishing with a compound like cerium oxide or diamond paste on a felt pad for a brilliant shine, all while keeping the stone wet to manage dust and heat.  

Basic Steps to Making a Cabochon

1. Select & Prepare Stone: Choose a rough stone, then cut it into a basic shape (like an oval) using a saw, ensuring the back is flat.
2. Rough Grinding (Shaping): Use a coarse wheel (e.g., 80 grit) on a lapidary machine to establish the basic dome shape and define the edge.
3. Fine Grinding (Smoothing): Move to finer grit wheels (e.g., 180, 220 grit) to refine the dome and remove deeper scratches from the rough grind.
4. Sanding: Progress to even finer grits (like 600 grit) to smooth out all remaining marks, checking for evenness under a bright light. It's best to check this when the stone is dry, a wet stone will hide many flat spots and scratches.
5. Polishing: Use a felt pad with a polishing compound (like cerium oxide or diamond paste) and water to bring the stone to a high-gloss finish.
6. Clean & Inspect: Thoroughly clean and dry the stone to check for any dull spots or scratches, repeating the polishing step if needed. 

 Key Tips

• Use Water: Keep the stone and grinding wheels wet to prevent dust and overheating.
• Work Systematically: Always move from coarse to fine grits and check your work frequently.
• Safety First: Wear safety goggles and work in a well-ventilated area.