Cabochon
/KAB-uh-shon/
Definition
A gemstone cut with a smooth, rounded, domed top and a flat or slightly domed bottom, without facets. Used for opaque or phenomenal stones to showcase color, pattern, or optical effects.
The cabochon (or 'cab') is the oldest form of gemstone cutting, predating faceting by millennia. Rather than cut with flat, angled surfaces (facets), a cabochon is shaped and polished into a smooth dome with a flat or slightly curved base. Faceted stones rely on angled planes to reflect light and create brilliance. Cabochons rely on a continuous curved surface to show body color, luster, and optical phenomena that faceting would break apart. This cut is ideal for opaque stones (turquoise, lapis lazuli), stones with special optical effects (star sapphire, cat's eye chrysoberyl, moonstone), and stones with interesting internal patterns (agate, jasper). Certain stones are almost always cut en cabochon because their value depends on effects that only a domed surface reveals. Opals need a smooth dome to maximize play of color. Star sapphires need a high dome oriented along the crystal axis to display asterism. Cat's eye chrysoberyl needs a domed face to concentrate chatoyancy into a single moving line. Hardness plays a role in cutting style. Softer stones (below 7 on the Mohs scale) are often easier and safer to cut as cabochons than as faceted gems, which require crisp edges that can chip on delicate material. The shape maximizes the visibility of asterism (star effect), chatoyancy (cat's eye), and adularescence (moonstone sheen). Cabochons can be circular, oval, or freeform, and the height of the dome varies from low (flat) to high (steep).
Usage in the Trade
Cabochons are used in rings, pendants, earrings, and brooches. They are the standard cut for opals, star sapphires, star rubies, moonstone, turquoise, and many semi-precious stones. Bezel settings are the most common mounting for cabochons.
Examples
Star sapphires are always cut en cabochon because the domed surface is what creates the six-rayed star effect (asterism). Faceting would destroy it.
Opals are almost exclusively cut as cabochons. The smooth dome maximizes the play of color visible to the eye.
Jade, turquoise, lapis lazuli, and moonstone are classic cabochon stones. Their beauty comes from body color, luster, or optical effects rather than sparkle.
Frequently asked questions
What is a cabochon cut?
A cabochon cut is a smooth, polished dome with no facets and a flat or slightly curved base. It is used for stones valued for color, luster, or optical effects rather than brilliance from light reflection.
Which gemstones are cabochon?
Common cabochon stones include opal, moonstone, star sapphire, star ruby, turquoise, jade, cat's eye chrysoberyl, labradorite, lapis lazuli, and agate. Any opaque or phenomenal stone that loses value when faceted typically stays a cab.
Is a cabochon more or less valuable than faceted?
It depends on the stone. For sapphires and rubies, faceted cuts usually command higher prices when clarity and color are strong. For opals and star sapphires, cabochon is the only appropriate cut, and a well-domed stone with strong optical effect can be extremely valuable.