I’d be very dissassified with this answer. There are such things as curses attached to particular objects, quite apart from any intention that you may or may not have with regards to your use of it. If you are in the state of grace, and ignorant of the occult connection, the chances are that you’ll be mostly protected (invincible ignorance), at least spiritually, if not necessarily mentally, or physically. On the other hand, any willing connection to things associated with the occult is dangerous, even if it is only passive association. It is a form of tacit consent. The Devil exists, AND is active in many ways, whether or not one believes A. in his existence, or B. in his activity (particular or general).
This mirrors the whole idea of sacramentals having value in and of themselves (although, absent faith, they are less efficacious, if at all). Carrying around a blessed rosary is an implicit act of Catholic faith. Likewise, any association with a crystal that has been “blessed” for occult purposes is tied to the occult, and potentially dangerous. You’re opening an unnecessary door, and there is no reason to presume that the Devil won’t make use of it in some way. Any willing, avoidable, association with them is at least objectively sinful. We’re supposed to actively denounce Satan and his works, not simply pretend they don’t exist.