Fasetten

Fasetten are flat polished surfaces that form the outer faces of a cut gemstone. They are created by gem cutters to influence how light enters, travels through, and exits the stone. The term is used in Dutch and German, among other languages, to describe the facets on a cut gem.

A facet is ground at a precise angle to maximize light reflection and refraction, contributing to the stone’s brilliance, fire, and scintillation. In practice, gem cutters arrange facets in a pattern that divides the stone into crown facets (top) and pavilion facets (bottom), with a table at the largest upper facet and a culet at the tip. The girdle forms the stone’s outer boundary. The modern brilliant cut, which is common for diamonds, typically has 57 or 58 facets; emerald and other step cuts use fewer, larger facets arranged in parallel steps.

The faceting process uses specialized equipment, including a faceting machine with rotating laps and diamond abrasives. The rough stone is shaped, then facets are added and polished in successive stages, with tight control of angles, symmetry, and finish. Quality considerations include facet alignment, polish quality, girdle thickness, culet size, and overall symmetry.

The design of facets affects optical properties: brightness (brilliance), dispersion (fire), and scintillation. Different gemstone species, such as diamonds, rubies, and sapphires, respond differently to specific facet patterns due to their refractive index and hardness.

Historically, faceting evolved from early simple cuts to modern multi-facet patterns as cutting technology advanced, particularly in the 18th–20th centuries.