Can crystals in a velvet bag be used in crystal healing, or does the velvet block the energies?

I have a crystal in a velvet bag, said to protect it from absorbing foreign vibrations. Can i still use it while it’s still IN the bag to meditate ot heal with, or will the velvet block all/most energies?

I’m using it to heal another person in a ‘projection of healing energy’ sense, rather than to absorb the negativity; and i don’t want to let the crystal absorb the foreign vibrations of that person in the process.