i found it that the gold coalesced, upon swirling the solution again became colloidal, filtered it through cotton, i suppose you may stuff it in oven at 100*C with lid loosely on and let it cool back down again, in labs they have "autoclaves" which are basically large disinfection ovens for handling biological matter
nanosilver should work, but ive found some of my nanosilver solutions went bad, noticable bacterial odor