A Rough Diamond

In 2017, the Lesedi la Rona, the largest rough diamond found in more than a century, was sold for US$53 million to a London jewellery company. After a year of analysis, the company has turned the rough gemstone into at least sixty smaller valuable diamonds. 

When a newly-discovered diamond is in its natural state, it is called “a rough diamond”. This expression can be used metaphorically to describe a person. 

Polly is a rough diamond（有潛質而未經琢磨的人）. If you give her good training, she will become a capable actress. 

Just like an unrefined stone that will become a sparkling jewel after being professionally cut and polished, Polly has some good potential or characteristics that are hidden and not well developed. 

This idiomatic expression also refers to someone who has a good character at heart but is impolite and uncultivated. 

Peter always looks untidy, but he is a rough diamond （外粗內秀的人）. 

The figurative meaning was used as early as 1624 in a tragicomedy “A Wife for a Month” written by the British playwright, John Fletcher. 

“She is very honest, and will be as hard to cut as a rough diamond.” 

An alternative form of this saying is “a diamond in the rough”. Similarly, its basic meaning is that the diamond is in an imperfect or unfinished state before the craftsman does his work. 

Give this candidate a chance. I think he is a diamond in the rough. 

In reality, a lot of people are like rough diamonds or diamonds in the rough. So do not simply look at their appearances.