JL asks: “I was given a very pretty crystal ball as a gift. I don’t want to use it and don’t know how to use it and have no intentions of learning how to use it. Its just a pretty object. Any harm in keeping it as an art object?”
Yes. Objects used in the occult arts often come with a “blessing” placed upon it by the manufacturer – and it’s not the kind of blessing that will bring joy and peace to your home!
Crystal balls, also called crystal gazing balls, are used for scrying – which is an occult art of divination through the use of reflective surfaces of some kind, such as water, mirrors or crystal. Psychics claim to receive visions while gazing upon these surfaces through a kind of trance induction. Some practitioners believe they are receiving visionary experiences of super- or preternatural insight while others say their visions arise from the subconscious mind. Scrying is most commonly done with a crystal ball, but it is also done with any smooth surface, such as a bowl of water or a pond.
The Catechism condemns any and all kinds of divination, including that of scrying. (See No. 2116-2117)
I’m sure your friend meant well, but crystal balls aren’t an appropriate decoration for a Christian home. For this reason, I recommend not only removing this object from your home, but also that you destroy it so that it does not fall into anyone else’s hands.