I don't turn these on a lathe. I do some operations on my metal lathe, but most of the work is done on other machines.
Diamond slab saw, lubricated with mineral oil.
Diamond core drills, lubricated with water.
Grinding and polishing wheels, lubricated with water / oil mix.
Aha!! Thank you, that does help. Beautiful work BTW I had a friend of my in MO that turned Granite and some soapstone on his lathe and he used some type of light oil and he always stated how messy it was.