Gelaterias near the Duomo are mostly industrial mix. Real artisanal gelato: Vivoli (oldest in Florence), La Carraia, Gelateria dei Neri.
Real gelato sits flat in tubs (not piled high) and uses muted natural colors.
A cone with 2 flavors is the standard. Most places offer free whipped cream — 'no panna' if you want to taste just the gelato.