Fetching details from the dictionary...
gem; jewel; precious stone
彼女かのじょに宝石ほうせきをプレゼントしたよ。
I gave her a jewel as a gift.
宝石ほうせきの輝きかがやきはとても美しいうつくしいよね。
The sparkle of jewels is very beautiful.
この宝石ほうせきはとても高価こうかなんだよ。
This jewel is very expensive.