Ceramic floor tiles.

I used a permanent marker to disguise a scratch. Wiped it off the face before it was fully dry. Don't forget it will take on colour from whatever you are colouring over (a bit like watercolours).
I also coloured in some piping under a washbasin with a marker and it looks amazing! Well, actually it doesn't because it's sort-of invisible now against the dark tiles behind it!

Thanks for your replies will have to have a good look don't know how deep they go .

Depending on the colour, bleach first, dry, then grout in a colour similar to the tile. Buff with fine sandpaper, then a bit of clear lacquer painted on to seal.

I had pale coloured ceramic floor tiles in the bathroom of my old house and one of them had got quite scratched where the door had scraped it. When getting the house ready for sale, I was told to get a bit of the time grout mixed and smooth that over the whole time and that would fill in any scratches. I did that and, once dry, I wiped it all off and buffed the tile up. I honestly couldn't see where the scratch had been (and it was a fairly deep scratch too).

What has caused the scratches Hulahoop? If they are dark marks you could probably bleach them, if they have cut through the glaze, not much you can do?