Quote - I made control edges by hand without using the bevel tool and it renders as it should with smooth on

Is smooth on in that right hand image? I don't see any smoothing, what smoothing angle do you have set for that object in Poser?

Once you have those control edges, you can increase the smoothing angle setting in Poser until those edges appear rounded, it'll give you more realistic looking stonework without ugly artifacts and without the need for actual bevelled geometry.