Do you know the origin? It reminds me of Niobe, which is Greek. It's pronounced nigh-OH-bee. Going with that I would say Niabi is nigh-AH-bee.
________________________________ Mulder: will you let me drive? Scully: I'm driving. Why do you always have to drive? Because you're the guy? Because you're the big Macho Man? Mulder: No, I was just never sure your little feet could reach the pedals.