quartz tiles 40*40

[carl0151]

Hi everyone new to the forum, gonna be putting quartz stone tiles down with silver speckals in on the back kitchen floor. The floor is concrete at the moment and needs 75mm sand/cement screed. Can i tile right over the screed or do i need to ply the floor and what adhesive should i use. I am thinking about putting diamonds in on the corners, but when i cut the corners of the tile it will not have the same profile as the other side of the tile . Whats the best way to get the same profile a bit of a shamfer. When i cut the corner of the tile of for the diamond how much of the corner should i cut of with the tile being 40*40. The tile are black with silver speckals and the diamonds or square cuts are gonna be red with silver speckals and how big should i make square cuts. Any help or ideas would be mostly appreciated thanks Carl.