Silver has a rich history as an antibiotic/anti-microbial. It just works. Water stored in silver containers stays fresh -- this is why the Roman Empire used them.
Where the controversy and confusion begin is, as usual, in modern times. I can't legally make any medical claim here, but I can say that the claims the medical industry makes about "silver turning you blue" are ridiculous when dosing properly. More info on the Blue Man hoax
Argyria results from prolonged contact with or ingestion of silver salts. Argyria is characterized by gray to gray-black staining of the skin and mucous membranes produced by silver deposition. Silver may be deposited in the skin either from industrial exposure or as a result of medications containing silver salts. 
Prior to 1999, colloidal silver was viewed as a "Pre-1938" drug and not subject to FDA approval.  Since that time, colloidal silver is no longer considered a pre-1938 drug  but can still be marketed as a dietary supplement.
Colloidal Silver by another name... Collargolum
By reason of its colloidal nature collargolum has vigorous catalytic effects which induce or enhance the processes of oxidizing bacterial toxins in the organism This fact was proved by Schedc Hamburger Robin and others Prof Solis Cohen Jour Amer Med Asso Oct 20 1906 stated It is quite probable that the therapeutic value of colloidal silver is largely due to catalytic action in taking up and again yielding thus destroying toxins bacteria or diseased cells a chemical amboceptor action to an illustration made familiar by Ehrlich through such action it may prevent or retard sepsis It certainly has a definite therapeutic action and should be employed more extensively in larger and more frequent doses The Railway Surgical Journal 1907 
Uses / Testimonials
- Forum dedicated to testimonials of colloidal noble metals NOTE: This forum speaks of "Meso" colloidals, produced & sold by PurestColloids.com. While the site owner does not appear to be related to the company, some of the posts look to be email/snail-mail, as if posted by PurestColloids.com. There are many posts that appear original and some give negative feedback(i.e. condition not resolved by product) so there is certainly value here.
- "I've recently started preparing my own colloidal silver and have been watering a couple of plants with it. This testing is on-going but no negative results observed and potential positives(will update after more controlled testing). I have personally used MesoSilver, MesoGold & MesoPlatinum in the past and have family that, as of Dec 2016 have been using store-bought colloidal silver and experienced reduced seasonal sickness/cold duration. Inspecting the bottle revealed it to be an ionic formula(clear) and obtained at a drug store in Cambridge MA. " --SEC
I'd love to collect some more information and even testimonials here. Perhaps you can help.