E. De Felice notes that this is a sporadic and today rare surname, derived from the old Christian name of a congratulatory and auspicious character Graziadei, with the variant Graziadio, which reflects the Latin expression gratia Dei: "grace, gift of God".

E. Rossoni agrees on the medieval Christian origin and specifies that the base name is Gratiadei, with the sense "thanks be to God". He also supplies documentary evidence: in the Codice Diplomatico Istriano, for the year 1310, a synod presided over by Archbishop Graziadio is recorded. As for its present distribution, Rossoni indicates that the form Graziadei, very rare, appears to be concentrated in the Trento area and in that of Potenza, while the variant Graziadio, scarcer still, would be proper to the north of the Cosenza area.