What defines two-phase inclusion in a gemstone?

A two-phase inclusion in a gemstone is defined as a hollow cavity that typically contains both a liquid and a gas. This type of inclusion can be observed during gemological examination, particularly with tools like a microscope. The presence of both phases allows for specific characteristics to be identified, such as the type of gas and the nature of the liquid, which can contribute valuable information about the gemstone's formation and geological history.

The liquid phase can enhance the visibility of the gas phase, creating distinct visual effects under appropriate lighting conditions. This phenomenon is significant in gemology because it aids in the identification and evaluation of gemstones, helping gemologists to distinguish between genuine stones and treated or synthetic alternatives. In contrast, the other options do not accurately capture the essence of a two-phase inclusion, focusing instead on other characteristics or treatments that do not define the specific nature of inclusions in gemstones.