noun
Refers to the green gemstone variety of beryl. Used in mineralogy and jewelry contexts.
彼女は緑玉石の指輪をはめている。
She is wearing an emerald ring.
エメラルド is the common loanword for emerald in everyday Japanese. 緑玉石 is a more technical or formal term, often used in mineralogy or traditional contexts.
Compound of 緑 (ryoku, 'green') + 玉 (gyoku, 'jewel') + 石 (seki, 'stone'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning 'emerald'.