beryl

This term serves as a categorical umbrella for several precious gemstones, most notably emeralds and aquamarines. While it can refer to the raw mineral in a geological sense, it is frequently used in gemology to describe the chemical composition of a stone before its specific variety is identified by color.

As a mass noun referring to the mineral substance, it is typically uncountable. However, when referring to individual crystals or specific gemstone specimens, it functions as a countable noun.