The Tyndall effect is an easy way to see if your colloidal silver solutions contain a significant amount of colloids. Pure ionic silver will give a very weak line when a red laser light is aimed through the solution. All solutions will contain at least a small amount of colloids even if the generator current was set very low. If there is a high colloidal silver ratio, a very distinct line will be formed.
You can easily convert from ionic silver to colloidal silver by adding a small amount of a reducing agent. Popular additives are Maltodextrin (A white carbohydrate powder) or Corn syrup. You only need a small amount and the Tyndall line will gradually increase as the ions are converted to nano particles. It is not possible to convert from colloids back to ionic so it is always a one way process. For this reason, you need an adjustable or current limited generator to produce pure ionic solutions.
You should never see sparkly flakes as these indicate poorly made solution with overly large particles usually caused by too high a current setting during production. Nano particles below a certain size are too small to be visible with this method but all colloidal solutions have particles in a range of sizes so will show some effect. A very intense Tyndall effect is a sign of large particle sizes. The ideal would be a faint line with no visible texture and no sparkly flakes.