rough diamond

According to the Daily Mail, the diamond was cut from a 236-carat rough diamond found in Botswana.

Joseph Mylchreest was a Manxman, a rough diamond but a man of sterling worth.

The soul is placed in the body like a rough diamond, and must be polished, or the lustre of it will never appear.

I dislike him, in spite of Aunt Betty calling him a rough diamond; but of course I wouldn't see him robbed or cheated.'

But he was studying, and he soon attracted the attention of the head of the business, who called him "a rough diamond."

If anyone seeks a polished crystal and finds a rough diamond, he is vexed; he does not recognise its value.