1. someone/something with hidden qualities or potential
he/she has a lot of hidden potential. He/she is a diamond in the rough
Someone who is described with the idiom 'a diamond in the rough' can be a person who is more talented clever or kinder than they first appeared to be. Diamonds are often unremarkable when found naturally and it is only through the process of cutting and polishing that they reveal their true beauty. Someone who is described as a diamond in the rough might need time to reveal their true talent or potential or maybe someone who is hiding hidden qualities that might later be revealed.