The International Bartenders Association specifies a Negroni with equal 30 ml measures of gin, bitter Campari, and sweet red vermouth, built in a chilled old fashioned glass over ice, stirred gently, and garnished with half an orange slice.
What the specification does — and does not — settle
It fixes the ratio, named bitter, build, glass, and garnish. It does not require one gin or one vermouth producer, one ice format, or one target dilution. Those open variables are where a useful comparison begins.
Make the published version first, then change one thing at a time. Record bottle names, strength, serving temperature, ice, stirring time, and the reason for the change. The result is a repeatable observation rather than a claim that one variation is universally better.
Primary source: International Bartenders Association — Negroni.
