Cabochon

Cabochon (also pronounced Cabachon) are gemstones that have been shaped to a rounded finish and polished instead of faceted. Usually oval in shape and with a flat bottom, cabochons are usually preferred for gemstones that have a low hardness rating on the Moh hardness scale and have many inclusions that would otherwise make the stone unattractive or even more brittle if faceted, due to having many sides that could expose a crack or imperfection to be easily damaged if struck. Instead, cabbing exposes a larger portion of the gemstone, while polishing increases the attractiveness and fills any gaps, cracks, or scratches.

Some gemstones, like star sapphires, have natural "star"-like inclusions that require cabbing in order to show the full effect.