This small change separates the edge of the table and top of the orange from the background wall slightly more, suggesting space between the edge of the table and the wall.

Note that increasing the three-dimensionality of these objects was the result of adding completely made-up gradations. Of course, when you are looking a painting subject, the light striking your subject creates the gradations that you observe and copy.

However, there may be areas of your subject that a particular light direction does not make look very three-dimensional; in those instances you may want to introduce some subtle gradations, consistent with the direction of the light source, in order to bring out the form.