A sable is a type of fur yes, but a sable is also a black or dark piece of clothing worn in mourning.... like mourning the death of someone.
I've heard a sable referred to as that black kind of netting that Stevie sometimes wears over her hats, covering her face.....
So Sable on Blonde would be that black netting on top of her blonde hair....
.... i think that is the imagery for the song title ....
