The round shape in feng shui decor is an expression of the Metal feng shui element. Circular decor items bring into your home the energy of clarity, preciseness, freshness and equality that is characteristic to the Metal feng shui element.
You have probably noticed that when you are in a space with big circular windows, for example, or a big round rug, your energy feels more refreshed, as well as more active.
The round shape activates your energy and keeps it going; it is a very active energy, even though expressed in a subtle way.
This is one of the reasons why a round table is the best shape for a table in many homes and businesses - it is the shape that allows for a free, fresh and equal flow of energy between all family or business members.