Tile Comes In Runs, Too

See the difference in color between the tile square in the bottom left and the others?

Look closely, and you’ll see that the tile above it is also slightly darker than the tile to its right.
These tiles obviously came from a different run , or batch . Just like wallpaper , tiles that are made at the same time with one batch of pigments will be ever so slightly different in shade from tiles made from another batch or run. That’s why it’s important to check the run number on the label , so only tiles (or wallpaper !) from the same run are used next to one another.