Region: General | Usage example: The launch was the acid test of their new marketing strategy.

Acid test

Meaning

A critical trial that proves the value or worth of something.

Used when describing a decisive, revealing test.

Origin notes can vary by region and source; this page gives the commonly reported explanation and usage context.

Chemical reference to acid dissolving fake from real metals.

Adopted into business and technology after chemists used harsh acids to separate metals.