Carrara White - Platinum Grey Tumbled Marble Brick Mosaic Tiles

Laid horizontally the courses stretch a wall, so a narrow shower enclosure or a splashback behind a run of units reads wider than it is. Turned through ninety degrees the same sheet lifts a low ceiling instead. A hexagon or a fan has no such axis and cannot be used this way; a brick bond can, and it is the cheapest spatial correction available in a small bathroom.

The offset does something with the colour as well. Because each course steps half a unit against the one below, the scattered grey pieces never stack into a vertical line. The eye keeps finding them in a new position, so the contrast stays lively without hardening into a stripe.

Tumbling rounds the ends and long edges of every piece, so the courses lose their machine regularity and read as something set by hand. That suits older houses, where a perfectly aligned mosaic can look imported into the room. Both marbles are calcitic and will etch on contact with acid, though a broken surface disguises it well. Seal before grouting.