This is my Friend Mike Helmer engineering the heck out of a large slab of rose quartz.

He made this round 800 lb sphere from material starting at 1700 lbs or so. about 1/3 of the total mass was removed to accomplish this.
Mike has said that a chunk this large tends to fracture before it is finished so great care is taken not to take off too much material in a single blow or grind.