Dwarf Jade Growing for Thickness and How the Trunks get Grey 

In order to get trunks thick (for any tree, actually), let them grow to the fullest extent. I usually wait two to five years before the first major cutback. While you can make a tree look older than it actually is with styling, only time can age the trunk. Even small trees can take on the patina of age but only after they've been growing for a adequate amount of time.