For quickly and precisely cutting large quantities of material, especially stone, a chopping machine is the tool to use.  Use a mosaic wet saw to cut 3/4" granite slabs into 3/8" thick rods.  Then use the chopping machine to cut into individual tesserae.  If you don't want to cut rods from a slab, you can purchase marble and granite rods from us in the stone section of our webstore.