Lapidary basics
Lapidary means cutting, shaping and polishing stone. People use different tools to make rounded stones, faceted gems and carvings.
Different cuts need different tools
A cabochon has a smooth, rounded top and usually a flat back. A faceted gem has many flat, angled faces. A carving may have grooves or a three-dimensional shape. A cabbing machine shapes rounded surfaces. A faceting machine holds the stone at set angles. Small grinding tips reach into carvings.
GIA explains the cutting styles; the carving tools reference covers the small tips and wheels.
What makes a cabochon
The rounded top, or dome, should curve evenly. Flat spots often show only after the stone dries. A flat back helps the stone sit in a piece of jewellery. Some cabochons have two rounded faces instead. GIA describes both forms.
From slab to polish
Start with a flat slice of stone, called a slab, that has no obvious cracks. Draw the shape you want. Use straight saw cuts to remove the extra stone, then use a wheel to round the outline and top. Each finer wheel removes scratches left by the one before it. A polishing pad and paste or powder give the stone its final shine.
Dry and inspect the stone between stages. If a deep scratch remains, return to a wheel that can remove it; polishing will not hide it. CabKing's step-by-step guide shows one machine and wheel sequence. The first-cabochon guide lists checks for each step.
Work wet and safely
Many stones contain silica. Grinding them can make fine dust that harms the lungs. Keep the wheel supplied with water, follow the machine manual, wear eye protection and keep electrical connections dry. Water reduces dust but does not make every exposure safe. US workplace guidance on silica dust recommends water and ventilation together; the CabKing manuals give instructions for their machines.
Identify a stone before cutting it so you can check for material-specific hazards. The first-cabochon guide lists stones to start with and stones to avoid. A local lapidary club may let you try a saw or machine with supervision before you buy one.