i would start at 1000 grit up to say 2000 wet not dry
polishing is removing material you are not adding, all you are doing is making the surface flat then you can polish with a compound on a cloth, or if you have the kit one of these
View attachment 300041
the difference being my polishing lathe spins at 10,000 rpm it takes seconds to polish a tip so in effect set the tip up in a drill clamp the drill in a vice then switch on sand wet and light, polish with compound say t cut then wax with beeswax etc and wash the tip in warm soapy water