Types of Gemstone Cuts: A Buyer's Reference
Gemstone cuts fall into four main families: brilliant cuts (which maximize sparkle), step cuts (which emphasize clarity and color), cabochon (a polished dome for opaque or effect stones), and rose cuts (a historical dome with facets). The cut a stone receives depends on its optical properties, clarity, and what the finished piece is intended to do with light.
Brilliant Cuts: Maximum Sparkle
Brilliant cuts use triangular and kite-shaped facets radiating outward from the center. The arrangement reflects light back toward the viewer from multiple angles, producing scintillation — the flashing "sparkle" associated with fine jewelry. The standard round brilliant cut has 58 facets: 33 on the crown (top) and 25 on the pavilion (bottom). According to the International Gem Society, approximately 75% of all diamond sales use the round brilliant shape.
Brilliant cuts are applied to several shapes, not only round. The cutting style — the facet arrangement — is constant; the outline is the variable:
| Shape | Characteristics | Common stones |
|---|---|---|
| Round brilliant | Circular outline; the reference standard for sparkle | Diamond, amethyst, sapphire |
| Oval brilliant | Elongated ellipse; looks larger per carat than round | Amethyst, sapphire, emerald |
| Cushion | Square or rectangular with rounded corners; vintage appearance | Sapphire, amethyst, diamond |
| Marquise (navette) | Pointed oval; finger-elongating effect in rings | Diamond, amethyst |
| Pear (teardrop) | Round on one end, pointed on the other | Diamond, amethyst |
| Princess | Square with sharp corners; technically a "square modified brilliant"; developed by Betzalel Ambar and Israel Itzkowitz in 1980 | Diamond, sapphire |
Oval and pear cuts can produce a "bowtie effect" — a dark zone across the center — if the proportions are poorly executed. This is a cutting defect, not a feature of the stone's material.
Step Cuts: Clarity and Hall-of-Mirrors Effects
Step cuts arrange rectangular facets in parallel rows ascending the crown and descending the pavilion like a staircase. Instead of the rapid scintillation of brilliant cuts, step cuts produce flashes of light from broad flat facets — sometimes described as a "hall of mirrors" effect. Because step cuts offer a direct window into the interior of the stone, inclusions are more visible, and clarity becomes more important.
| Cut | Characteristics | Common stones |
|---|---|---|
| Emerald cut | Rectangular or square with cropped corners; 58 facets; named after the stone it suits best | Emerald, aquamarine, diamond |
| Asscher | Square with heavily cropped corners and deeper pavilion than the emerald cut; developed by Joseph Asscher in 1902; produces more fire than standard step cuts | Diamond, aquamarine |
| Baguette | Small narrow rectangle; typically used as an accent stone alongside a central gem | Diamond, sapphire |
The emerald cut's name derives from practical origins: the rectangular shape and cropped corners reduce stress fractures when cutting emeralds, which commonly contain natural inclusions (called "jardin") that make them susceptible to chipping.
Cabochon: Dome Without Facets
A cabochon is a gemstone shaped into a polished, unfaceted dome with a flat back. It is the oldest gem cutting technique. Cabochons are used for stones that are opaque, heavily included, or display optical effects that a faceted cut would disrupt:
- Asterism (star effect): a star pattern visible when lit from above, seen in star sapphire and star garnet, is created by intersecting needle-like inclusions that only appear as a star when the stone has a convex surface.
- Chatoyancy (cat's eye): a single band of light moving across the surface, seen in tiger's eye and cat's eye chrysoberyl, requires a cabochon cut aligned along the fibrous structure.
- Adularescence: the floating, billowing glow of moonstone is best displayed in a high-domed cabochon.
Cabochons are also the standard cut for opal (to display play of color), turquoise, malachite, and other stones where pattern and color take precedence over sparkle.
Rose Cuts and Mixed Cuts
The rose cut is a historical style with a flat base and a domed crown covered with triangular facets — typically 24 facets arranged in concentric rows. It produces less brilliance than a modern brilliant cut but has a distinctive antique appearance. Rose-cut gems are currently popular in vintage-inspired and Art Deco jewelry design.
Mixed cuts combine brilliant and step facet arrangements. The crown may be cut in a brilliant style while the pavilion uses step-cut rectangles, or vice versa. The radiant cut — a rectangular or square outline — uses a brilliant-cut pavilion, producing more sparkle than a standard step cut while maintaining the geometric outline of a square or rectangle. The Barion cut is another mixed style that places a round brilliant pavilion into a fancy-shaped outline to reduce the bowtie effect.
How Cut Choice Relates to a Stone's Properties
The cut a lapidary selects depends on the stone's optical and physical properties:
- High-dispersion stones (diamond, zircon) benefit from brilliant cuts that maximize the "fire" (spectral color flashes) produced by high light dispersion.
- Strongly colored stones like emerald or amethyst may be better served by step cuts, which let the color read clearly rather than breaking it into flashes.
- Heavily included or patterned stones receive cabochon cuts, since faceting would not improve their appearance and might reveal flaws.
- Directional optical effects (asterism, chatoyancy) require dome shapes aligned to the inclusion orientation.
For an introduction to the broader vocabulary of gem properties, including lustre and transparency, browse the gemstones directory or read gemstone vs crystal vs mineral.