I've cut and polished Silicon before- grind it, dont cut it. Use a diamond impregnated wheel for parting off- run it fast with stacks of flood coolant. To surface it use either lose abrasive with water or lose diamond abraisive, again water based, not oil based cos it makes a hell of a mess.
Remember Monocrystalline Silicon will machine much better than polycrystalline- the crystal orientation is important.POlycrystalline is a nightmare.
To polish it use Cerox rather than Rouge- Rouge will stain your hands, your clothing your walls and everything (don't ask how I know this lol).
I'm an optical engineer so these tips are based on making Silicon lenses for applications in the Infrared.
I used to diamond turn the stuff using moncocrystalline diamond tools which cost about 400 quid each, but even they didn't last very long on the stuff- it's as hard as a whores heart!
I love deadlines- I like the whooshing sound they make as they fly by.