Scratches on a marble floor: light, deep, and what each takes.
Marble is softer than people expect. Grit under a shoe, a dragged chair, a vacuum wheel: each leaves a line, and a few thousand lines read as a haze. The depth decides the fix.
Before anything else, work out whether it is a scratch at all. A scratch is physical: you can often feel it. An etch is chemical: dull, cloudy, not cut in. General wear is neither: a lane that has lost its reflection and makes every isolated mark look worse than it is.
The depth test
Run a fingernail across it. A mark you can see at an angle but cannot feel is in the finish and hones out. A mark the nail catches is in the stone and wants grinding before honing. Several scratches, dull pathways or a rough feel underfoot mean the floor needs the whole area restored rather than a spot repair.
The finish matters too. Polished marble shows every line because each one breaks a reflection. Honed marble hides them, and it also punishes a spot repair with a polishing product, which leaves a shiny patch on a matte floor.
Why the spot is the wrong unit
Restoration is finish matching. Polish one area without understanding the surface around it and you get a spot that is shinier, flatter or hazier than the rest, and that is more visible from the doorway than the scratch was. Sandpaper, scouring pads, toothpaste and multi-surface scratch removers all do this, and some add swirl marks and a pale halo for good measure. Shine sprays cover the scratch with a film that holds dirt and peels.
What a light scratch takes
Fine scratches on a polished floor come out with honing followed by polishing across the affected area, so the lane matches the edges of the room again. On a honed floor the same honing pass, stopped before any gloss, recreates the matte evenly.
What a deep scratch takes
A scratch the nail catches is below the finish, so the surface is ground down to it with coarse diamonds, then taken back up through honing and polishing. Deeper gouges and edge damage may not vanish completely without taking off more stone than a floor should lose; they are reduced, blended and honestly described beforehand. The floor is treated as one surface throughout, which is what produces an even result rather than a patchwork.
Keeping them off
Grit is the enemy: mats at every external door, a dust mop or a hard-floor vacuum before any wet cleaning, furniture lifted not dragged, felt under chairs. Acids are the other enemy, because a wine or juice spill etches even when it leaves no stain. A floor honed and sealed before the lanes go grey is a lighter job than one left until they do.
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Related questions.
Some tiles sit higher than others. Can that be fixed?
Yes. That is lippage, where adjacent tiles were laid at slightly different heights, and it is the main reason to grind a floor rather than just polish it. Grinding takes the whole floor down to one flat plane, removing the high edges so the surface reads as a single sheet of stone rather than a grid of tiles. It is more work than polishing alone and it produces the most dramatic result, because a flat floor reflects as one continuous surface. It also removes the edges that catch dirt and feet. Once ground, the floor is honed and polished as normal. How much can come off depends on the tile. A thick stone tile takes grinding easily, while a thin tile, or one laid over a floor that flexes, has less to give and is assessed first. Grinding is also the point where a floor is made properly flat for the first time, since most lippage is set at installation rather than appearing later.
Do you move furniture?
Yes, within reason. Sofas, dining tables, rugs and most freestanding pieces we move and put back. Fitted joinery, appliances and anything plumbed in stays where it is and we work around it, protecting it as we go. Very heavy or valuable pieces are best moved before we arrive, and we say which ones when we quote. A stone dining table is usually worked in place rather than moved, since it is heavier than it looks and the risk of damage in moving it is higher than the inconvenience of working around it.