Which two factors determine an inclusion's impact on a gem's value?

The impact of an inclusion on a gem's value is primarily determined by its position and relief. Position refers to where the inclusion is located within the gemstone, as some locations may be more detrimental to appearance and thus value than others. For example, an inclusion located centrally within a gem may be more visible and impactful than one situated near the edge or in a less noticeable area.

Relief, on the other hand, describes how readily the inclusion can be distinguished from the rest of the stone. An inclusion with high relief stands out clearly against the gemstone's surface, making it more noticeable and potentially lowering the gem's value. Conversely, inclusions that are less prominent or blend in with the surrounding material may have a less negative impact on value.

Understanding the interplay of these two factors helps in assessing the overall quality and desirability of a gem, which in turn influences its market value.