Prosciutto di Parma PDO is made from just two ingredients — Italian pork and salt — air-cured for at least a year in the hills around Parma, where the breeze does the rest. Every genuine ham is branded with the five-pointed Parma ducal crown.
The imitation is any generic ‘parma-style’ or ‘Italian’ cured ham without that crown. Look for the burned-in coronet and you have the real thing.