experienced yes, but I'm not sure it is truly incalmo. If I were to attempt making it, I would go about it in some different ways and so just as the one you see there would be no differential line between the 2 colors. It may be incalmo but there are other ways to achieve this same look. If I was running production of this piece it would be more economical to do it other ways than incalmo and still achieve this same look and use fewer assistants and have a smaller rate of rejections. Ivo, in my experience, one such as the one shown would require more than just 2 highly experienced blowers.