The Square Diamond Wall is a solid non-transparent bright blue shiny building-block with a chiselled slanted square on 4 sides and a centered even square with small links to the ledges of the block on 2 sides. It can be crafted in your Crafting Menu (default key "Q") or at any Crafting Table in worlds created before R22 on September 16th 2015, after the recipe has been unlocked upon buying it in the Store as a part of the "Diamond Decorative Pack" (as of R24 in November 2015). To craft 8 (blocks of) Square Diamond Walls, you'll need (as of R24 in November 2015):