Polished porcelain shows metal marks and other types of deposit marks because it is harder than the surface rubbing against it. That's the same reason that porcelain plates get gray knife marks on them. Those are not scratches, and should not have a strong abrasive used on them. All of those should come off with softscrub.

A quality porcelain tile like Neolith will generally have a MOHS hardness of 8, which is greater than most marbles (MOHS 3-4) and as strong as some igneous rocks, e.g. granite and quartz. The maximum on the MOHS Scale is 10, which is the hardness of diamond. It takes a whole lot of force and something very very hard, like a diamond, to actually scratch porcelain. Most porcelain will be the hardest thing in the room.

They are scratches. It's a gloss finish. Doubtfull if they're coming out cost effectively.

I visited Neolith company in Spain, where they come from and they told me right away, polished finished ( or glossy call the way you want ) will scratch! So I went with ultra soft and I am very happy with it! If ever you have strange stain on porcelain you can remove it with ( mix baking soda with peroxide and put it on for 39-60 sec or more and it will remove it all! Clean with water!