80 CENTESIMI

It's the only stamp of the set that had only one printing run (Fig. 1). At the "used" status it's the rarest stamp of the Old Italian States and one out of the rarest and most important of the world (1 letter and 5 single pieces known in total).

Fig. 1: 80 centesimi

Catalogued color shades (as per Sassone)

Olive bistre (typica color)
Bistre
Orange bistre
Orange