Monochrome design decision can work well with the marble tiles for bathroom walls. The best option is to use black and white combination. But you should be very careful otherwise may get a picture with to many colourful spots which is difficult for the perception. Remember that for the great picture the space must not have more black than white, but you are allowed to combine the two colours like on the chess board.
If you are more towards the idea of using many colours for the bathroom walls then you better select a pastel tones. Of course, you may use such bright colours as yellow and orange but they should not dominate the space and should be dissolved in the other colours. Vibrant bright colours would be better used to highlight ans accentuate the pastel tones.
But if you take a look at our gallery you may notice that a number of the pictures are made professionally following a certain idea and that’s true, because nowadays manufacturers are offering the whole set for the bathroom tile which are already matched between themselves.