Crystal pendulums can be very nice, from those made out of clear quartz to amethyst, rose quartz and what have you. Crystal pendulums will usually have many facets, while metal pendulums are usually more like cones or tear-shapes.
Some pendulums are hollow so that you may put something in it. It may be water, say with a homeopathic or flower remedy in it, or a witness that directs the energy towards its source. For instance, if you put somebody's hair into the pendulum, then such a combination should, in theory, be sensitive enough to diagnose the vibrations of that person, long distance, that is, even when the person is not physically present.
There are other shapes as well, one of which is the Eqyptian form, which is, they say, used for magical purposes... I personally prefer crystal pendulums, because they add their own frequency to the healing, but "empty" pendulums such as quartz or brass may be better for diagnosing.
Also, you may opt to have one "larger" pendulum to diagnose and clear the space in house, while using the other "smaller" pendulum to work with chakras.
To see a video of dowsing using a circular diagram, click here.