ForMatter/Finishes/cut/Round brilliant cut (gemstone)
finish_cut_round_brilliant

Round brilliant cut (gemstone)

cut · polished · RBC, Tolkowsky brilliant, 57-facet round brilliant, 58-facet (with culet)

The classic 57-facet diamond cut Marcel Tolkowsky published in 1919 — geometry tuned to maximize the return of light through the crown. Every modern engagement-ring brilliant traces back to this paper. Designed for diamond's 2.42 IOR; performs well on sapphire, ruby, CZ, moissanite with matched proportions.

57 facets (table, 8 bezel + 8 star + 16 upper-girdle on the crown, 16 lower-girdle + 8 pavilion on the pavilion); a 58th culet facet historically added on small diamonds to protect the point. Tolkowsky-ideal proportions: table 53%, crown angle 34.5°, pavilion angle 40.75°, depth 59.3%, polish + symmetry Excellent. AGS / GIA grade cut on optical-performance and proportions. Other diamond facet families: princess (square brilliant, 49–58 facets), emerald (step cut, 50 facets, mirror staircase), Asscher (square step), oval / pear / marquise / heart (modified brilliants).

character — fire (spectral splash) and brilliance (white return) at full design IOR; bright, glassy, faceted.

Finish properties

  • levelpolished
  • subcategoryfacet style
  • applies togemstone

Second life

reversibilityzero — gemstone facet styles are subtractive and committed once cut; "re-cutting" produces a smaller stone with different proportions. The original cut is permanent.
blocks substrate recyclingno
renewabilitymoderate — chips and edge wear can be re-polished with minor weight loss; major damage requires full re-cut to a new pattern.

GIA Diamond Grading and Identification literature; AGS American Gem Society cut-grading standards.

Citations