How do I properly cut pre-existing kitchen backsplash tile for new low voltage wall plates?
Tile setters use carbide tipped nibblers to trim tiles by small amounts. You would need to have access to the back of the edge you want to trim off so you can grab it with the trimmers. You take small bites, clip clip clip, until you have removed what you need to. There is still the possibility of cracking the tile, but this is your best bet for trimming small amounts off ceramic tile.