The staircase and railings were drawn for a wealthy gentleman, they must be installed in his summer cottage. He liked this project, but still don’t order it)), these wrought railings were   made for other customers many times.(photo 4 is one of them) It was also suggested many different colors of marble.  

Below are photos of the project with Sketchup + V-ray

Metal Staircase and Wrought Iron Railings with Marble-1

Metal Staircase and Wrought Iron Railings with Marble-2

Metal Staircase and Wrought Iron Railings with Marble-3

Metal Staircase and Wrought Iron Railings with Marble-4