2D representation of the diamond unit cell

In a 2D projection of the diamond unit cell, the base plane of the unit cell ABCD is shown by a square and the atoms in the base plane are shown by their z co-ordinates. The face-centered atoms of all 4 side faces are projected down and shown by numbers showing their height from the base in terms of the lattice constant a. Figure gives how the 3D unit cell is depicted in an equivalent 2D representation. All atoms whose z-co-ordinates vary by ¼ are nearest neighbours included in the tetrahedral bond. Thus the nearest neighbour distance would be that between say A and atom at J.