Rocks in ear butter - safe?

I have a friend who wants to start stretching their ears, and for their birthday I was going to make them a batch of my ear butter. They are witchy inclined, so I would also like to personalize it with some crystals/rocks. Obviously ones that are not porous or soluble, and could be sanitized (I was thinking baked in the oven to kill everything). I just don't know if that could potentially fuck up the mixture / crystals being super unsafe or anything like that.

Any advice is appreciated :)