For the home user, an accurate pH reading of your colloidal silver can be made using Hydrion pH paper, which is only sensitive to hydrogen ions, and therefore is not bothered by silver in the solution. Hydrion paper is available in different ranges, so make sure you get one which reads within a few units of 7.
There is a silver generator dealer who claims his CS has a pH of 10, and one of the members measured it with a silver based pH meter and it did indeed read 10. He makes a big deal out of this claim probably so he can cash in on the alkaline water craze. However the actual pH is no doubt less than 8. Measurements of my CS are in the range of 7.2 to 7.8 using Hydrion paper which is accurate to .2 pH units.
Alkaline solutions feel soapy, slippery. At pH 10, it should be noticeable.