gemcutting

Gemcutting, also known as lapidary work, is the craft of shaping, cutting, and finishing gemstones to enhance their beauty, durability, and usefulness in jewelry. The practice transforms rough mineral material into polished stones through controlled grinding and polishing, while minimizing waste.

Two main outcomes are cabochons and faceted gems. Cabochons are smooth, domed shapes typically used for opaque or chatoyant stones. Faceting involves creating flat faces arranged around a table to maximize light reflection and dispersion in transparent gemstones such as diamonds, sapphires, and garnets. The cut is planned by considering color, clarity, crystal orientation, and inclusions to balance beauty with yield.

Typical steps include evaluating the rough stone, preforming by sawing or cleaving, blocking a basic shape, grinding and sanding with progressively finer grits, and final polishing. For faceted stones, the gem is mounted on a dop, facets are cut on a faceting machine with precise angles, and the surface is polished with fine diamond pastes. Safety and precision are important, as dust and tool wear can affect results.

Equipment includes diamond saws and trim saws, grinding wheels or laps, faceting machines, polishing laps, dop sticks, and magnification tools. Materials range from natural gemstones to synthetic or treated stones, each with different hardness and response to dulling and heat. Quality depends on cut, symmetry, polish, and overall balance, contributing to light performance and value; the Four Cs (color, clarity, carat, cut) are commonly referenced in jewelry contexts, though gemcutting focuses on the cut.

The technique has ancient roots in early lapidaries; modern faceting developed in the 19th and 20th centuries with mechanical diamond-cutting and the concept of the ideal cut proposed by Marcel Tolkowsky in 1919. Contemporary gemcutting uses advanced abrasives and precision equipment to optimize brilliance and symmetry.