Colloidal Silver is made up of tiny nanoparticles of metallic silver suspended in liquid that cannot be removed through a normal filtering process. Ionic Silver is dissolved silver or silver ions dispersed in liquid, usually water. While Ionic Silver has the same antimicrobial properties as Colloidal Silver, it contains no metals.
The difference between Colloidal Silver and Ionic Silver can be demonstrated by the Tyndall Effect. A Tyndall test shows the effect of light scattering as a light beam passes through the liquid. If a laser beam is shined through a true solution without micro-particles, the light will pass cleanly. As seen in Colloidal Silver, the laser beam is reflected off the particles creating a visible path of light in the liquid.