facetcut

Facetcut is a term used in gemology and gemstone manufacturing to describe the arrangement and execution of flat surfaces, or facets, on a cut gemstone with the intent of enhancing light performance. The facetcut determines how light enters, reflects, and disperses within the stone, producing brilliance, fire, and scintillation. The term is derived from facet and cut and is commonly used interchangeably with facet-cut or faceted cut in trade literature.

Faceting of gemstones began with simple table cuts in the late medieval period; the development of modern facet patterns culminated in the 18th–19th centuries with the round brilliant cut for diamonds and later optimized cuts for colored stones. The facetcut is realized through specialized machinery and skilled handwork that shape and polish each facet to precise angles and tolerances. The process typically includes mapping the stone, selecting a facet plan, rough cutting, creating the table and crown facets, adding girdle facets, forming the pavilion facets, and executing the final polish. The goal is symmetry, precise angles, and a smooth finish that maximizes light return while minimizing oblique losses.

Common facetcut patterns include the round brilliant (the most widespread pattern for diamonds, typically with around 58 facets), the emerald cut (a step-cut with parallel facets), the princess cut (a square or rectangular brilliant-cut with many small facets), and the cushion cut (a softly rounded square or rectangle). Cut quality is assessed by light performance and finish; labs may grade diamonds as Excellent or Very Good for cut, symmetry, and polish, while colored stones emphasize facet geometry and alignment.

Beyond jewelry, facetcut concepts also inform the faceting of synthetic crystals used in optics, where facet arrangement influences optical performance.