Just a note about Purpleheart....its a very opened grained wood, and tends to be brittle. It will check/crack easily in thinner cross sections.
I personally don't use it because of the open grain....no matter how finely you sand it, if it even comes near a buffer the grain will load up with compound. The best way I have found to finish it is to use MANY coats of Tru-Oil.... apply a coat and immediately wipe it off, let dry for two hours, light hand buff the finish with fine grade steel wool and then go through the whole process again, and again, and again....until the surface grain is filled. In my experience it usually takes several days and about 15-20 coats of Tru-Oil to accomplish.