What is the definition of a cavity in gemstone terminology?

In gemstone terminology, a cavity refers to an internal opening that extends from the surface of the gem. This means that it originates at the exterior and penetrates into the stone, creating a void within. Cavities can occur due to various processes during the formation of the gemstone or because of subsequent exposure to environmental conditions.

Understanding this definition is important in gemstone evaluation, as cavities can affect the value and durability of a stone. Unlike other types of flaws or inclusions, which may not necessarily connect to the surface, a cavity has a clear entry point that can impact how light interacts with the gem and, subsequently, its aesthetic appeal.

The other options relate to different aspects of gemstone quality and characteristics; however, they do not accurately capture the specific nature of a cavity as an internal opening.