I always thought of Sade as a very stylish singer, but not necessarily a great one; kind of weak, actually. A model who could sing a bit. I was wrong. Watch these concert videos.
The thing is, Sade always sounds a little off. But consistent. Maybe she does it deliberately, certainly no one else sounds like Sade. She gets a little raspy down low, but she displays more range here than I've heard on her studio recordings. And not to forget the band, they are tight.
Sade is a lot more than just a great looking record cover, although, of course, she's that too. Not a model who could sing - Sade is a singer who could model.
The key is the shallow angle between the saddle and the string. A proper guitar bridge has a sharp break between the saddle and the string. This shallow angle causes the classic sitar buzz. This is a very easy part to make from any decently hard wood. A scrap of fretboard blank is ideal. A little experimenting, and you will get it. Then you can convert any guitar into a "sitar".