A listello or border tile is a decorative piece, usually mesh mounted that is different from the field tile in shower or kitchen backsplash.
(:1f539:) What material is a listello made of?
A listello is made of any material really. Natural Stone, glass mosaics, ceramic tile and even cast metal. The most popular would be natural stone.
(:1f539:) Is there a proper height to add a listello?
It honestly is left to the imagination. I would say most common in a shower setting would be "eye height" to where you can see it. However, this is not a right or wrong place to add it.
(:1f539:) Will adding a listello cost more money?
That is a good question, it can add cost to the job since it is probably more than the tile that would take its place. However, how do you put a price on a design element if to really completes the project look.