Hi all! We are putting in a pool that has a large wall across the back. In the center portion of the wall we are doing a black/gray glass tile with a white ledgerstone on the sides. The white ledgerstone will have a white pool coping. I wanted the black glass tile to wrap around the top of the center portion but I have been told that it needs something not so slick. The pool tile company we used does not have anything in a dark black/gray coping. Does anyone have any suggestions on what we could use?

I read that granite can be used but I wasn't sure if that would be slick too. PLEASE HELP! Pics below of the wall and tile.