Thank you for your inquiry. Removing a ghost is not something to be taken lightly. There are many different types of paranormal activity including residual energy (where a ghost may just be a memory loop of a past event) or intelligent, where they can communicate with you. Before attempting removal, I highly suggest reading Michelle Belanger's, The Ghost Hunter’s Survival Guide. I would also read articles on the TAPSwebsite.Both of these resources can give you a better idea of what to do and what not to do.
Although I prefer crystals not to be drilled, their potency depends on the individual crystals. Some may lose their energy and others are fine with it. I would base it on a crystal by crystal basis.
I hope that these recommendations can be of assistance and that crystals grace your journey with love and light.
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*Disclaimer – Crystals are not a medical treatment and should not be used as a replacement for medical care. Please consult your healthcare specialist for your particular needs.