What is the term for a gem that is colored by an element included as part of its basic chemistry?

The term for a gem that is colored by an element included as part of its basic chemistry is idiochromatic. This concept is crucial in gemology as it describes gems whose color is an inherent characteristic due to their chemical composition. For example, the presence of chromium in emeralds gives them their green color, making them idiochromatic.

In contrast, allochromatic gems acquire their color from trace elements or impurities, which are not part of the gem’s primary chemical makeup. Literal and monochromatic do not relate to the gem's color due to its chemical structure, making them irrelevant in this context. Understanding the distinction between idiochromatic and allochromatic gems is fundamental for identifying and evaluating colored stones accurately.