beryl

1. (uncountable, mineralogy) A mineral of pegmatite deposits, often used as a gemstone (molecular formula Be₃Al₂Si₆O₁₈).Examples: "The sunset had been magnificent, and the Thames was floating in dark radiance; the waves wearing that transparent clearness, which gives more the idea of melted beryl, than aught else: every little circle in the water had that trembling light which characterises precious stones."; "Although there are dozens of different types of gems, among the best known and most important are diamond, ruby and sapphire, emerald and other gem forms of the mineral beryl, chrysoberyl, tanzanite, tsavorite, topaz and jade."uncountable

2. (countable) An example (a stone) of the mineral beryl.Examples: "The crown was set with six beryls of excellent size and color."; "The appearance of the wheels and their work was like unto the colour of a beryl […]"; "His buskins were laced with gold, and from his belt hung a sword, narrow of blade and keen, the hilt rough with beryls and black diamonds."countable

3. (uncountable) A dull blueish green color.uncountable