The (real) diamonds are very expensive.

yes

Explanation:

real diamonds are really expensive

Mallam was treated that way due to the fact he belongs to the low-class society. In Ghana, there are different social classes: The upper class where the rulers, nobles and similar people are part of it. The other is the middle class and the last one is the low and working class where Mallam is part. They have different rights, that's why Mallam does not have the right to speak before the higher class.