diamond in the rough
US /ˈdaɪ.mənd ɪn ðə rʌf/
UK /ˈdaɪ.mənd ɪn ðə rʌf/

1.
diamante grezzo, talento nascosto
a person or thing that has great potential but is not yet refined or polished
:
•
The young artist was a true diamond in the rough, needing only guidance to shine.
Il giovane artista era un vero diamante grezzo, che aveva bisogno solo di guida per brillare.
•
The old house was a diamond in the rough, with good bones but in need of renovation.
La vecchia casa era un diamante grezzo, con buone fondamenta ma bisognosa di ristrutturazione.