Pendulums are divination tools, used to answer yes/no questions to assist in providing direction.  They work by responding to your subconscious mind.
 
Lapis Lazuli
Associated with Throat and 3rd Eye chakras
Lapis Lazuli is a thought amplifier that helps to open your third eye and aids you to speak your thoughts.  This stone is helpful in strengthening the connection between you and your spirit guides.
 
This listing is for 1 pendulum intuitively chosen by me.