Cabochon :

A cabochon, often referred to simply as a “cab”, is a popular and versatile style of gemstone cut that is commonly used in jewelry making. Unlike faceted gemstones, which have multiple flat, polished surfaces and angles, cabochon-cut gemstones have a smooth, rounded, and polished surface without facets.

Cabochons are used with a wide variety of gemstones, including both common and rare types. Some of the most popular gemstones cut as cabochons include moonstone, labradorite, opal, turquoise, and many varieties of quartz (such as amethyst and rose quartz). Cabochon cutting can bring out the unique characteristics of each gemstone.