Prism Glass Tile (Perfection Pressed Prism Tile), made by Condie-Neale Glass Company Saint Louis, circa. 1914 or earlier. The 1914 Condie-Neale Catalogue for 1914 describes the design as “Geometric”. It is 5 inches square with some small flects,chips to the edge and corners–see picture.

The design could be considered an example of seven-dimensional space–(7-polytope) or 7-simplex. See Wikipedia “Seven-dimensional space”. The geometrical definitions came years later than 1914, when this design on the market.