Question

Rough diamonds may sometimes be mistaken for worthless pebbles. Meaning

Answer 1

it would mean some times great gift of a person are not being seen

Answer 2

We tend to think that diamonds are beautiful as long as they are in jewelry store or in some precious jewelry. Rough diamonds look like ugly rocks and we forget their value. A diamond is a gem but we forget that because we mistake it as a pebble. A rough diamond could be worth millions, pebbles are worth nothing. Same way people with potential and integrity can be unfairly judged maybe because they come from a poor family. So basically it means that sometimes we tend to forget the real potential of a human being and misjudge him because of some external factors.