A gem's cut has two parts: its shape, the outline seen from above, and its style, the arrangement of facets or surfaces. An oval sapphire and an oval diamond share a shape, but either could be cut in a brilliant style with triangular facets or a step style with long parallel ones. Knowing both terms helps you describe a stone and understand why it looks the way it does.
Shape versus cutting style
Shape is the face-up outline: round, oval, cushion, pear, marquise, emerald (octagon), heart, trillion and so on. Cutting style describes how the facets are laid out, and it largely decides how the stone handles light. Brilliant styles break light into many small flashes. Step styles show broad flashes and long reflections, like looking down a hall of mirrors. Cabochons have no facets at all.
Cutters choose both shape and style to suit the rough. A long tourmaline crystal favors an elongated shape. A stone with strong color zoning may need an orientation that hides the zones. Cutters of colored stones often trade some brightness for weight, since colored gems are usually sold by the carat.
Brilliant cut
The brilliant style uses triangular and kite-shaped facets that radiate from the center. It is designed to return as much light as possible through the top of the stone, with strong brilliance and fire. The round brilliant is the best-known example, with 57 or 58 facets. Brilliant styles also appear in oval, pear, marquise, heart and cushion shapes, and many colored gems are cut as modified brilliants with extra or rearranged facets.
Step cut
Step cuts have long, rectangular facets in rows parallel to the girdle, like the steps of a staircase. The emerald cut, a rectangle with cut corners, is the classic step cut. It was developed partly to protect emerald, which tends to chip at sharp corners. The Asscher cut is a square step cut with deep cut corners, and the baguette is a small rectangular step cut used as an accent. Step cuts show color and clarity openly, so inclusions are easier to see, and they have broad flashes of light instead of sparkle.
Mixed cut
Mixed cuts combine a brilliant-style crown with a step-cut pavilion, or the reverse. Many colored gems are cut this way. The crown shows the shape and gives some sparkle, while a step-cut pavilion can save depth and weight or improve color. The princess and radiant cuts used for diamonds combine square or rectangular outlines with brilliant-style faceting, and the patented and branded cuts page describes them.
Cabochon
A cabochon has a smooth, domed top and usually a flat or slightly domed base. Opaque and translucent gems, such as turquoise, jade, opal and moonstone, are normally cut this way. Cabochons are also needed for phenomenal gems. Star sapphires and star rubies, cat's eye chrysoberyl and tiger's eye need a dome oriented to the internal needles or fibers, or the star or eye will not show. High domes give a sharper eye, and cutters judge dome height to balance effect and weight. The gemstone optics page explains these effects.
Rose cut
The rose cut has a flat base and a domed top covered in triangular facets that rise to a point. It was common in the 16th to 18th centuries, especially for diamonds, and it gives a soft, flickering look in candlelight. Rose cuts are usually shallow, so they look larger for their weight. They have returned to fashion in modern jewelry, both in diamond and in colored stones. The history of diamond cutting traces how the rose cut fit between the table cut and the brilliant.
Briolette
A briolette is a teardrop or pear-shaped stone faceted all over, with no table or flat base. It is often drilled at the top and hung as a pendant or earring drop. Briolettes were popular in Indian and Victorian jewelry, and cutting them takes skill because every facet must line up around the stone.
Checkerboard
A checkerboard cut, also called a buff-top or chessboard cut, has a top covered in square or diamond-shaped facets in a grid. It catches light with many small reflections and works well for gems with strong color, such as amethyst, citrine and topaz. Some checkerboard stones have a smooth cabochon-like base or a faceted pavilion.
Fantasy and carved cuts
Fantasy cuts combine flat facets with curved, carved or concave surfaces, often on the back of the stone so reflections multiply. German cutters in Idar-Oberstein, including Bernd Munsteiner from the 1960s onward, did much to establish the style, and many contemporary gem artists work in it. Concave faceting uses curved laps to cut scooped facets. The modern gem cutting technology page explains the tools behind these cuts.
Common shapes
| Shape | Description | Notes |
|---|---|---|
| Round | Circular outline | Brightest return in diamond; most common diamond shape |
| Oval | Elongated round | Looks larger face-up than a round of the same weight; can show a bow-tie |
| Cushion | Square or rectangle with rounded corners and curved sides | Old mine cut ancestor; popular for colored gems |
| Pear | Rounded at one end, pointed at the other | Point needs protection in a setting |
| Marquise | Long oval with points at both ends | Also called navette; points chip easily |
| Emerald (octagon) | Rectangle with cut corners | Usually step cut |
| Heart | Two lobes and a point | Needs good symmetry to look right |
| Trillion | Triangle, often with curved sides | Used as center stones and accents |
| Princess | Square with pointed corners | Brilliant-style faceting |
| Baguette | Small narrow rectangle | Step cut accent stone |
Bow-tie effect
Elongated brilliant shapes such as ovals, pears and marquises can show a dark area across the center shaped like a bow tie. It happens when light leaks out of the pavilion in that zone instead of reflecting back. A shallow bow-tie is normal. A strong one makes a stone look dull, and buyers compare stones face-up to judge it.
Choosing a cut for a gem
Diamond's high refractive index rewards precise brilliant cutting. Colored stones with lower refractive indices need different pavilion angles to avoid windows, see-through areas in the center of the stone. Gems with cleavage, such as topaz, need care so a facet does not lie parallel to a cleavage plane, which is hard to polish. Pleochroic gems are oriented for the best color through the table.
Durability matters too. Pointed shapes like the pear, marquise and princess are more prone to chipping at the tips. A protective setting such as a V-prong or bezel helps. The gemstone settings page covers these choices.
Frequently asked questions
Is "cut" the same as shape?
No. Shape is the outline, such as oval or pear, and cut style is the facet arrangement, such as brilliant or step. Cut quality, a third meaning, describes how well the stone is proportioned and finished.
Which cut sparkles most?
Brilliant styles produce the most sparkle and fire. Step cuts give broad flashes and show color and clarity more openly.
Why are some gems cut as cabochons?
Opaque and translucent gems show color and pattern best as smooth domes, and stars and cat's eyes appear only in cabochons cut to the right orientation.
What is a window in a gem?
A window is a washed-out, see-through area in the center of a faceted stone. It happens when the pavilion is too shallow for the gem's refractive index, so light passes through instead of reflecting back.