Reverse the classic with black subway tile and white grout.
Grout color for white marble tile.
The light gray is also a fine choice but keep in mind that it will darken and maybe not match the tile color quite as well over time.
And now to grout colours which i get asked about a lot so here s a hot tip.
For white tile floors i often specify grout that matches the colour of natural stone below.
Pick a brightly colored tile and neutral grout.
This is because i have been in hundreds of bathrooms over the years that were filled with white tile and yes you guessed it dirty white grout.
Use a non sanded grout to protect both the marble and the grout from discoloring too much.
Or go with a neutral tile and colored grout.
You can even have white subway tiles with aquamarine blue grout if you desire.
One of the most popular choices in home design today is white tile with gray grout.
Why not get creative.
Neutral colored grout in shades of gray or white match nearly all colors and patterns without overwhelming the tile or looking too monochromatic.
But subway tile comes in many colors and grout in almost as many colors.
Depending on the color of grout used the look of carrara pietra porcelain tile can vary once installed.
Different grout colors for tile can produce startling contrasts or smooth out and make a design more cohesive depending on your tile and grout choices so do your research thoroughly.