People often create hazed patches on polished marble surfaces simply by using the wrong cleaner. Anything like vinegar or most glass cleaners will actually etch the surface of marble, requiring re-grinding of the surface. This is not just some substance sitting on the marble that needs to be cleaned off, the marble has been etched like frosted glass and needs to be re-polished.
Sealing to prevent stains
The best defense is to seal a stone countertop properly before the first use. Well sealed, most stains will be on top of the sealing material and not down into the pores of the stone. Proper sealing, like proper polishing, requires different products and techniques for different stones -- hence some expert advice.
Grinding and RePolishing is what is often required on stone
Professional polishing is done with machines and diamond grinding stones of very fine grit. Rob Ebeyer of the Marble Clinic in Mississauga, Ontario walked us through the use of his DIY marble re-finishing kit.
The refinishing is done with special grit pads that look like the kitchen ScotchBrite pads and a handled pad. The key is both the pad and the grinding compound that is used. A first grit is used to actually remove the etched surface. You have to work hard with a lot of elbow grease and pressure. Don't let the compound dry. Keep it wet, keep it moving and then wipe it off. Work on a small area at a time. Once the etched haze is totally gone, shift to a finer pad and a finer cream to polish up the surface. You can finish with a sealer, but the shine comes from the polishing, not the sealer. The Marble Clinic's kit is about the only one available that will give you the proper grinding creams to get the job done.
A little known accessory to the FEIN MultiMaster Oscillating Tool is a marble polishing kit, designed specifically for small area touch-ups. You are not going to buy this professional tool just to do one piece of marble, but if you do have the tool for renovation work, the marble refinishing accessory is worth it. It has a series of aluminium oxide pads that with a bit of water, or better yet, with the creams from the Marble Clinic's kit, would fix up any stain in no time. The only caution is this kit will get you to a very high shine quickly and you need to make sure you stop at the level of shine that you find on the rest of the piece.
To take out a scratch you do need power equipment as no amount of elbow grease will remove enough marble to get to the bottom of a deep scratch. Small scratches can be dealt with using aluminium oxide paper and water, followed by the polishing kit.
If you are trying to work with Granite stone, it is very different than Marble -- much harder. Granite requires different compounds and mechanical tools. It is not really a DIY task because of its hardness.