I am not a mason but am curious to learn why you flame bluestone?
You flame the ends of the stone to remove the "sawn" edge to match the thermaled top. Usually only needs to be done where the edge will be seen like a stoop edge, stair treads, etc... Bluestone cannot be "faced" with a chisel, hydro-splitter, etc..., at least not in my experiences.
I still snap a lot of bluestone treads. 1/8" score all around work all around with a tracer. The newer premium sawed stuff doesn't even need to be scored.