There are 3 reliable tests.
1) Color is yellow to dark amber confirms silver content.
2) We can easily test our Colloidal Silver with a laser pointer pen. The laser beam should show brightly in the liquid. It cannot be seen in water, as described in this video: https://www.youtube.com/watch?v=IYde8aK-9S4
3) Use a TDS Meter to check for conductivity through the liquid.
Does your silver pass these 3 tests? Then it is very likely to be good,