Silver Tests
This information has not been approved by the FDA: Disclaimer

FDA Regulations:  According to Federal regulations, colloidal silver must be manufactured in a registered FDA facility and be subject to strict quality control. Distributors of colloidal silver should be issued a certificate of analysis from the company from which they buy colloidal silver. This analysis should specify purity, microbiology testing, silver particle size, concentration (ppm), and use of chemical stabilizers, pH, and color. 

Before buying a silver product, you should ask for the following minimum information:
1. specify purity
2. microbiology testing
3. silver particle size
4. concentration (ppm)
5. use of chemical stabilizers
6. pH
7. color
Bob Beck and G. Henry Collins suggest a more extensive request for information:    Evaluating suggestions

There are several "common sense" tests that you can perform to determine the kind of silver product you have.
Most silver products are ionic silver because it is cheap and very simple to make.

How To Test for Ionic Silver: "To figure out whether a solution is ionic silver, you only need add chloride ions. Common table salt, which is sodium chloride, will do. If silver ions are present the chloride ions will combine with the silver ions and create a white, cloudy appearance. To form a cloud that is visible requires that a sufficient concentration of silver ions be present, typically about 10 ppm or above. Simply place 1-2 ounces of ionic silver in a clear glass. Add a few grains of table salt. Observe whether, as the salt dissolves, a white cloud of silver chloride forms in the solution. If so, eventually, the entire solution will turn cloudy. If more salt is added, the white silver chloride will become denser until all the silver ions have combined with the available chlorine ions. If no silver ions are present then no white cloud will form. Here is the rub: Some products will not make a white cloud of silver chloride when table salt is added because they contain no silver at all, or very little silver. Believe it or not, lab analysis has shown that some "silver" products actually contain no silver!"
[ 10. Colloidal silver list of diseases: truth about ionic silver ASL ]   [ 78. AS Lab tests for silver ]  [ 80. Lab tests for silver ]  [ 81. Patrial list ionic products ]

Testing For Silver Protein:    To find out whether you have a silver protein product rather than a true silver colloid, look for these characteristics:
Makes foam: When shaken, a silver protein product produces foam above the liquid that will persist for minutes after being shaken. This is probably the single most reliable indicator. Even when the product label identifies the product simply as colloidal silver and never mentions the word protein, this indicator will signal the presence of a protein binder. Shake the bottle and look for foaming. When the foam persists, protein is present.
Concentration: Silver protein products tend to have very high concentration values, typically in the range of 30 to 20,000 ppm. Concentration is expressed in parts per million (ppm) and is numerically the same as milligrams of silver per liter of water (mg/L).
Color: The color ranges from light amber to almost black with an increasing concentration of silver. Dangers Due to the high concentration of large silver particles, silver protein products are known to cause argyria, a condition that causes the skin to turn blue-gray." colloid reports  Silver Genesis: art of making it  [ 10. Colloidal silver list of diseases: ]