How do you cut or drill through a fixed wall mirror to mount a light fixture?
The question was about drilling an hole in a mirror. I think the correct way to do this is to mark out where the hole is required, get some putty and form a cupped mound below, fill with varsol or white spirit, and drill the hole slowly with a special glass drill bit. You must keep the bit lubricated with the liquid to dissipate heat and prevent the mirror from cracking.