First off here s a look at the gray grout i chose i went with a light gray option called frost.
White marble tile with light grey grout.
Depending on the color of grout used the look of carrara pietra porcelain tile can vary once installed.
Same 1x3 marble tile diffe grout color wow what a white marble hexagon tile with grout carrera floor gray and white marble kitchen reveal maison de pax tech silverado grout color pebble shower floor marble that hampton carrara marble backsplash done zo chris loves julia marble hexagon with mapei silver grout images master bath.
Use a non sanded grout to protect both the marble and the grout from discoloring too much.
White grout is a risk in bathrooms though as everyone mentions.
Gray grout will emphasize the dramatic gray veins that mimic real carrara marble while the white grout will the porcelain floors light bright and elegant.
This pic shows how the white subway tile and gray grout look in both shadowed spaces underneath the upper cabinet and to the left of it and in a more sunny spot close to the countertop.
Since i did an inset cubby with the same penny hex the grey seemed like the best option.
Same 1x3 marble tile diffe grout color wow what a difference floorwhite or light gray grout for carrera marble tile floorgrout color with.
In the bathtub i continued with the same light grey grout with white subway tile.
I do love the slight contrast but would have been happy with white white too.
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.