Translation guide
In Japanese, the concept of 'precious stone' is most commonly expressed by 宝石 (hōseki), which covers gems and jewels broadly. More specific terms exist for particular types of stones, and some expressions are used in idiomatic or metaphorical contexts.
The broad, everyday word for any precious or semi-precious stone, often used in jewelry.
The standard word for 'gem' or 'jewel'. Covers diamonds, rubies, emeralds, etc. Used in both casual and formal contexts.
She is wearing a ring with a precious stone.
I bought a necklace at a jewelry store.
When referring to a particular kind of gem, use the specific Japanese name.
Diamond. The most common precious stone in engagement rings.
A diamond is used in the engagement ring.
Ruby. A red gemstone.
Emerald. A green gemstone.
Sapphire. Typically blue, but can be other colors.
Expressions where 'precious stone' is used metaphorically to describe something valuable or rare.
Means 'like a gem' or 'gem-like'. Used to describe something beautiful, brilliant, or precious.
Her eyes sparkle like precious stones.
Literally 'jewel box', often used metaphorically for a place or thing filled with treasures or beautiful things.
This museum is truly a treasure chest.
When emphasizing the natural, unpolished state of a gemstone.
Rough gemstone, uncut stone. Often used metaphorically for someone with raw talent.
He is still a diamond in the rough, but I look forward to his future.
The word 石 (いし) means 'stone' or 'rock' in general. To specify a precious stone, use 宝石 or the specific gem name. Saying 貴重な石 (きちょうな いし) is possible but sounds unnatural; 宝石 is the standard term.
Her birthstone is a ruby.
エメラルドのネックレスが欲しい。
I want an emerald necklace.
サファイアは９月の誕生石です。
Sapphire is the birthstone for September.