試金石
Meanings
1
touchstone (assaying tool)
Literal mineralogical use: a dark siliceous stone used to test the purity of precious metals by the color of the streak left on it.
A touchstone was used to test the purity of the gold.
2
touchstone; test; litmus test
Figurative use: a standard or criterion by which something is judged or recognized. Often used in phrases like 〜の試金石となる (serve as a touchstone for ...).
This project will serve as a touchstone of his ability.
The election is a litmus test of trust in the government.
Usage patterns
- 〈事〉が〈物・事〉の試金石となるX serves as a touchstone/test for Y
This match will be a touchstone for his true ability.
- 〈物・事〉を試金石にするto use something as a touchstone/test
They plan to use the new system as a touchstone before expanding it to other regions.