What is the best crystal to get for protection against bad supernatural presences and to strengthen my bond with my guardian angel?

If you were to ask me that first question back in the 1980s, regarding the best crystal for astral protection, I would have answered that a quartz crystal is best, as I attended a seminar that espoused that quartz amplifies thought. But I have learned a great deal since those days, have done many experiments with quartz crystal, and have found that it does not in fact amplify thought, nor does any other crystal or gem. There is no magical item in physical terms that can, by itself, ward off inferior spirits or a bad astral presence. As to the second question, regarding how to strengthen one's bond with someone on the Other Side, like a guardian angel, spirit guide, or discarnate companion: simply radiate purified love from the heart to that person on a daily basis. That is the fastest and most efficient way to strengthen the bond with anyone on the Other Side.