宝石
ほうせき · houseki · JLPT N3 · noun
gem
💎 宝石 = treasure (宝) + stone (石): a treasure stone
宝 (hou) means treasure, as in 宝物 takaramono, treasure. 石 (seki) means stone, as in 石油 sekiyu, petroleum or rock oil. A gem is simply a stone worth treasuring.
宝 — roof 宀 + jade 玉 (simplified from 寶)
Originally written 寶, showing a roof 宀 over jade 玉, a jar 缶, and shell 貝 (money) — valuables kept safely at home. The simplified form 宝 keeps just the roof and jade, preserving the core idea of 'treasure.' It now means treasure, precious, or valuable.