What is "a diamond in the rough"?

[Mickey]

Business English Lesson, Advanced Level

ESL/EFL Test #146 "Hiring the Right Person", question 5

If the applicant seems to be over-qualified for the position, you have found either a diamond in the ......... or someone very adept at interviews.

(a) coal
(b) mine
(c) rough
(d) shop

Business English Lesson, Advanced Level

ESL/EFL Test #146 "Hiring the Right Person", answer 5

If the applicant seems to be over-qualified for the position, you have found either a diamond in the rough or someone very adept at interviews.

Correct answer: (c) rough

Your answer was: correct
_________________________

What is "a diamond in the rough" ?

[Mister Micawber]

diamond in the rough = a person of fine character but lacking refined manners or graces.
_________________
Native English teacher at Mister Micawber's

[Kitosdad]

Usually referred to in the UK as " a rough diamond."
_________________
If you need me, I'm here.