My first recollection of ever being exposed to dowsing was when I was very young and my sisters would dowse with a necklace to see how many children and of what genders they would be.

I currently have two pendulums, one of quartz crystal and the other is blue sodalite.  There were several of the quartz crystal when I was shopping for one at The Crystal Ark, all of which I picked up and played around with to figure out which one was right for me.  There were a few that danced around for me and I purchased the one that was the most active in my hand.