I work in stone conservation and for the body that dictates these regulations, even if it was built out of stone it would be required to be visually distinct. The only exception is if it were reinstatement of an original feature that had been demolished or decayed to the point that it had to be removed and fully rebuilt. In that case every effort should be made to source the stone from the same quarry, and the same mortar mix should be used.
Maybe to not be misleading about what is original and what is new
I think you could tell when it goes from stone to plastic.
I work in stone conservation and for the body that dictates these regulations, even if it was built out of stone it would be required to be visually distinct. The only exception is if it were reinstatement of an original feature that had been demolished or decayed to the point that it had to be removed and fully rebuilt. In that case every effort should be made to source the stone from the same quarry, and the same mortar mix should be used.