Check out this project post by Aalta Design Group, a plaster finishes specialist from Miami, Florida. The material is three coat venetian plaster over curved and swooping walls. The recesses, top (for lighting) and bottom (where the baseboards should be, but aren’t), both help to pick up the marble flooring, as the gleaming white floor seems to glide PAST or THROUGH the wall. A good place to note that venetian plaster is made from crushed marble dust, in part, and the photo shows the kinship between the materials, wall and floor. Visit the ADG website and read their blog post about what makes a truly great venetian plaster. You may not have a strong opinion on the topic, but apparently it makes a difference in the result.
List of Venetian Plaster Specialists.