diamond in the rough
US /ˈdaɪ.mənd ɪn ðə rʌf/
UK /ˈdaɪ.mənd ɪn ðə rʌf/
1.
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.
•
The old house was a diamond in the rough, with good bones but in need of renovation.