In fact, it will change after being worn on people for a long time, because people's secretions will have a slight chemical reaction with those things, which will be obvious after being worn for a long time.
The magnetic field effect promoted by crystal is not the magnetic field in science, but the magnetic field in metaphysics. In metaphysics, good magnetic field and bad magnetic field are positive energy and negative energy. Crystals have strong positive energy, and some crystals can also absorb negative energy. That's how crystals work. It is not a scientific function, but a metaphysical function (geomantic omen, five elements, etc. ).