Imperial Jadeite and Diamond Art Deco-Style Ring.
The phrase en cabochon (from French: knob) is the term applied to a gemstone with a smooth, domed top. Cabochons have no facets, are usually highly polished, and generally have a round or oval outline but can be any shape, including triangular, navette and rectangular. Aside from the domed top, the reverse can be slightly domed, completely flat or convex. Since ancient times en cabochon has been a popular cutting style for gems. Certain gemstones rely on the cabochon cut to realize their full potential. Asterated and cat’s-eye stones would not display their stars and eyes without the curved top of the cabochon cut. It gives moonstones their adularescence or billowy effect, and opal‘s play-of-color is best displayed by this cutting style. Opaque stones with layers and other multi-colored inclusions, such as agates, benefit from the cabochon cut to maximize the display of their features. Andradite garnets cut en cabochon are referred to as carbuncles. More valuable gems such as ruby, sapphire and emerald are also cut en cabochon but usually in an attempt to deepen their color, display a star or an eye, and/or disguise the number of inclusions they contain. Higher quality transparent and translucent gems with few inclusions are usually faceted with the exception of fine jadeite, which is always cut en cabochon.