I have had the exact problem you are having none of the suggestions above have worked. It seems that smokey quartz d I especially this alot. I learned how to facet mostly on smoky quartz. For a better lack of words it seems that smoky build up a harden shell after its first polish. I have had to go back to a fine grit lap very lightly hit the facets again then using 50 aluminum oxide for the 1st polish then 100k diamond spray then 200k graves is the name brand but any kind works. This procedure gives the best polish I ever done on smoky quartz. I have often wondered if the b smoky quartz really builds up a very hard and resistance film sometimes. This has never happen on amethyst or clear quartz just smoky quartz. The quartz came from hiddenite N.C. I often wondered if the area it comes from has something to do with it.