A diagonal I think would be much more difficult. Contact a home store, like Lowes or Home Depot, to ask their design specailists.
The very light and the tiles stick with medium shade colors the tiles stick with medium shade colors the very dark color grout.
Diagonal looks bigger. Do a dry run to see what kind of pieces you would wind up with on the edges or divide your inch measurements by 16.75in. Then, whatever fraction you are left with, multiply this by 16.75. Divide this number by 2 and you will have the inches of diagonal pieces on the edge.
Like this….
12ft x 12ft room is 144in x 144in. Divide 144 by 16.75 “which is the approximate width of the diagonal.” You will have 8.597. Take the .597 multiply times the 16.75 and you will have 9.99in. Divide by 2 and you will have 5in of partial diagonals on the edges. So point being, you will use 8 full tiles and 2 pieces that are 5inches diagonally.