Earlier quoted context omitted.
Yeah, I'm pretty sure that nobody tries to cut granite on site with an angle grinder. It's so difficult because the material is so hard. Granite countertops are typically cut off-site with a waterjet, which creates zero dust.
I wonder why those parts are not made in the desired shape already with no need to cut or sand in place.
Since it's a luxury but not a super expensive product, the more expensive process of precise measurement, off-site waterjet/laser cutting is not suitable.