The consulted works concur in deriving this surname from the Italian term pietra ("stone"), whether as a direct reference to the material itself or as the basis of place names that incorporate the word. It is also noted that many surnames derive from the personal name Pietro — itself from Latin Petrus, meaning "rock" — since the two etymological paths, the appellative and the topographic, frequently converge around the same root.

E. Rossoni indicates that the surname may originate from specific localities bearing the element pietra, such as Pietra de Giorgi and Silvano Pietra, in the area of Pavia, or Pietra Marazzi, in the area of Alessandria. Geographically, Rossoni traces its distribution along an arc running from the areas of Bergamo and Milan through those of Pavia and Piacenza, extending toward the area of Genoa.

R. Brondolo adds a specific historical attestation: bearers of the surname coming from Savignone, in the province of Genoa, are recorded in the canton of Ticino, Switzerland, from 1830, where they worked as scassadoo — a Ligurian dialect term designating those who cleared land and built terraced retaining walls. Brondolo also notes that the surname admits several possible interpretations, all linked to the concept of stone.

Rossoni further mentions the variant Pietramale, a rare surname that could derive from the place name Pietramala, in the area of Florence.