I've been testing out pendulums charged using elemental energy for each of the 4 elements. I made several pendulums all the same, only metal on a string and no stones either. This way there would be no question about whether a stone could be adding any magical properties to it.
To charge them a Rune symbol of the element was used in the color used for charging. The Runes are...
In the past I had done much testing already for the element water. For many years have used one as a personal pendulum. Traditionally Water is good for people who are better at feeling things and Air is for the mentally guided and oriented thinkers. I've found Earth is another possibility too. Here are some colors...
Air-yellow or yellow/white
I found that red works for fire but feels to much like raw electrical energy when you use the pendulum. Orange feels gentle and is the same for use.
Pendulums charged with the element fire behaved differently than the others. They are no different for yes/no questions but hold one over a map and they find energy or city power grids, earthquake fault lines. Also they locate weapons such as knives, even gun ammunition, natural gas lines, electrical wires that are hot. Once I had one charged that way start swinging toward my batteries sitting on the desk. Finally realized it would test my batteries, tell me which ones still are good. Never spent the money for a battery tester, but no need to now. The pendulum charged with the color orange and the Rune for Fire, is working fine. It will swing over good batteries and motionless when a battery is low. The low batteries will still power a TV channel changer and not my wieless mouse for the computer. I have tons of old AA batteries some over a decade old. This is proving to be a very useful pendulum.