It may be that you have lately heard something about a blue-grey skin discoloration after using colloidal silver. Again this is no colloidal silver but ionic silver that is the cause of what is happening.
Where a skin discoloration has occurred is when people have tried to make colloidal silver at home. It is impossible to make real colloidal silver at home. When one makes it at home, it is dependant on the method, between 80 to 100% ionic silver. Quite often one would like to have high concentrations (between 50 ppm and 500 ppm) and so salt is added in order to speed up production.
Through adding kitchen salt, sodium chloride (NaCl). Large particles of silver chloride are formed. It is a well known fact that a skin discolour ration may occur due to the ingestion of silver chloride. This phenomenon is called Argyria.
It is absolute nonsense to connect this to real colloidal silver at a concentration of 10 ppm and a particle size of 0.65 nanometers, a factor of a thousand smaller than the silver chloride particles. Real Colloidal silver of this quality can never be a cause for Agyria.