The blue crystals are indicators. They will turn pink when the silica gel is saturated with moisture.
You can regenerate your silica gel crystals by placing them in a heat proof container and baking them in the oven at about 250-300º F for a couple of hours. When the crystals turn blue again, it's ready to use.
The blue crystals are no different than the other crystals except that, when they were manufactured, they were doped with cobalt chloride. They should not have any negative effects on the items they are stored with.
Museums use silica gel with blue indicator crystals to preserve and store precious objects with. If there were any negative effects from it, they would not use it.
However, cobalt is a somewhat toxic substance. Wash up after handling and before eating, etc. and, of course, don't eat them.
You can regenerate and reuse silica gel crystals virtually indefinitely provided you keep them clean.