When I try to powder polish a botticino marble it gets dull spots. The more I polish the duller these spots get. I’ve tried rehoning with a higher grit and I still get dull spots. Is there a way I can polish without getting dull spots?

Some botticino marble have areas that are soft. These soft areas are the cause of the dull spots you describe. The polishing powder is eroding these soft spots. There are several techniques for polishing these dull areas. First, do not use polishing powders. Attempt to polish the marble by honing to a very high grit. I would take the marble up to at least 1800 grit and possibly higher. Second, you can polish the floor using a marble polishing disc or a polishing brick. The disc and bricks are composed of polishing powders but are molded into a hard block. Because the powder is not loose, it won’t erode the dull spots.