A bagua mirror has an octagonal frame (usually made of wood) with a round mirror at its center. The coloring and decoration of the frame can vary, but many bagua mirrors are painted with the colors red, gold, and green, representing summer, late summer, and spring, respectively.
Each side of the octagonal frame has three lines—known as a trigram—symbolizing an aspect of life. The section at the top of the frame has three unbroken lines and represents heaven. It's important to hang a bagua mirror so that this section is at the top. For the same reason, most bagua mirrors have only a single hanger that is placed at the top of the frame.
The shape of the mirror itself is very important, as it determines how the mirror works and should be used. Bagua mirrors can be flat, concave (bowing in, like a bowl), or convex (bowing out, like a dome). Flat mirrors are considered neutral and can reflect both good and bad energy. These can be used either indoors or outdoors, much as you might use a standard decorative mirror indoors for feng shui cures. Concave and convex mirrors should be used outdoors only and can have very different applications.