Moral damages are a form of compensation decreed by a court in instances where the defendant suffers:
physical suffering, mental anguish, fright, serious anxiety, besmirched reputation, wounded feelings, moral shock, social humiliation, and similar injury.
Calling someone a negro could cause wounded feelings. Mind you I've been called worse. It might be difficult to prove, unless you have witnesses and then you might have to prove the extent of your wounded feelings.
It also depends on the law of your land. It might not be an offence. As stated earlier it is an offence in the UK. It may be also that, if it happened in the course of your work that the company has policies regarding this which you could use to gain redress.