Low Grade Silver has nanoparticles that take forever to work.
You have to look for:
The Highest PPM
The Smallest Particle Size which cant get any smaller than a single atom.
The clearest solution that is Crystal Clear as water.
Pay attention to the fact that many producer of CS warn you not to refrigerate the product, not to expose it to the sun or high heat conditions, not to mix it with anything else.
That because of the chemicals used in its manufacture, those warnings are the CLUE that tells you that there are chemicals that will not react well with other substances or with extreme temperture conditions.
REAL Colloidal Silver has atomic size particles and you can mix them with other drinks, even with TAP water.
Beware of others that promote Meso Silver, even though they have been around here for some time, they have actually done a diservice by not reporting all the facts.