I have absolutely nothing against Tibetan silver beads at all, but they are actually an alloy that most likely has no silver content at all, so I really can't see the point in using sterling findings with them.
Generally I think it's best not to mix sterling with plated and/or base metals, as it just devalues the sterling in the piece rather than raising the value of the piece.
You also have the issue of tarnish, though as Tibetan has (most often) no real silver in it, the other metals it's made from may or may not tarnish and there's no real way to know how long it might take or if does tarnish at all!
