It’s obvious that this was done by smacking one stone up against another stone. /s
—
Yes and with copper tools (2.5-3 hardness) carving out diorite granite (6-7 hardness) - also it’s a fragile stone, one wrong strike and the whole is ruined. Such tools are obviously able to put mirror finishes of this sort of stone as well as create tolerances from 0.0003 to 0.001 inches from true.
Isn’t it amazing what a copper chisel and a piece of stone can do? Why even a cave man ...
Well, it’s pretty obvious that the ancient Egyptians invented sandpaper, or more correctly, sandpapyrus.
One thing they do have plenty of is sand!