In order to be classified as a gem, a mineral must possess which three qualities?

To be classified as a gem, a mineral must possess the qualities of beauty, durability, and rarity. Beauty is subjective but generally refers to the aesthetic appeal, which includes color, clarity, and brilliance that make the gem visually attractive. Durability is crucial as it indicates the gemstone's ability to withstand wear and tear over time, factoring in hardness, stability, and toughness. Rarity enhances the value and desirability of a gem; the less common a mineral is, the more coveted it becomes among collectors and jewelry enthusiasts.

While other options mention various characteristics, they do not encapsulate the essential qualities required for a material to be considered a true gem. For instance, being heavy or large does not necessarily relate to the beauty or desirability of a gemstone, and attributes like being shiny or colorful do not encompass the critical aspects of durability and rarity that define gemstones. Therefore, the combination of beauty, durability, and rarity provides a well-rounded criterion for gem classification.