How to condense a melted wax in to small aggregate forms like stones of different sizes?
Part of your problem is that wax is an amorphous solid and a mixture of various compounds.  This causes it to have no specific temperature that can be defined as a melting point, but rather a range of temperatures where it transforms from a hard brittle solid to a soft plyable solid to a liquid. 
The best I can recomend is that you first pour very hot wax into a much larger amount of ice cold water to form wax shot.  Then take the shot and a propane torch, torch the wax beads as they fall to partially melt the surface of the shot and that may get you your desired effect.