Here are a few ways to check for colorfastness in beads:
Lay a few beads on a damp white towel and wait a few minutes. If there is even a faint ring of color where the bead was, the bead is not colorfast.
Place stone beads into lukewarm soapy water and watch for a color change in the water
Place a small amount of acetone on a cotton swab and rub a section of the stone or bead that is least likely to be seen in a design. Please remember that chemicals can be harsh on stones, hands, etc. so use caution, like using rubber or latex gloves. If any color transfers to the swab it is not colorfast.