A lapidary lathe is a machine on which gem material is held in a chuck or collet and rotated against a tool, in contrast to the more familiar lapidary equipment in which the lap rotates and the stone is held against it. Lathes are used for sphere cutting, bead drilling, hollow turning of vases and bowls, and inlay channel work. Although less common than faceting machines and cabochon grinders in modern lapidary shops, the lathe remains the standard tool for certain forms.

Configurations

Sphere-cutting lathes use a pair of opposed cup-shaped diamond tools that the operator advances symmetrically toward a roughed-out cube of gem material; the spheres of carved nephrite, agate, lapis, and other ornamental stone seen in collections are typically lathe-cut and finished. Hollow-turning lathes, used in Idar-Oberstein and historically in the Russian imperial workshops at Yekaterinburg, mount large blocks of malachite, rhodonite, lapis, or agate on a heavy spindle and shape vases, urns, and bowls with diamond-impregnated tools fed by a cross-slide. Bead-drilling lathes (sometimes called pearl drills, although pearls and stone beads use slightly different tooling) hold a bead in a chuck while a fine diamond drill enters from one or both sides.

Skill

Lapidary lathe work is among the more demanding lapidary disciplines because the stone is in motion, the tool is in contact under cooling, and the geometry of the result depends on tool path rather than on a fixed cheating index. Sphere-cutting in particular requires repeated rotation of the workpiece between cycles to bring different facets of the cube into contact with the cups, since the lathe alone cannot generate a true sphere from a cube without operator intervention. Hollow turning is taught in Idar-Oberstein workshops and rarely outside that tradition.