diamond in the rough

diamond in the rough noun
plural diamonds in the rough
diamond in the rough
noun
plural diamonds in the rough
Britannica Dictionary definition of DIAMOND IN THE ROUGH
[count] US
1 
: a person who has talent or other good qualities but who is not polite, educated, socially skilled, etc.
— called also (British) rough diamond
2 
: something that is in poor condition but that is likely to become valuable with appropriate care or attention