Because agate will change when worn for a long time, it will become particularly round and smooth, some will change color, or something similar to bloodshot will be produced. This is actually a physical change, which has nothing to do with immaterial phenomena. Discoloration usually goes from shallow to deep, which is caused by people's long-term contact. Things that are rubbed for a long time will form an oil film on the surface, and places where stone tablets and pillars in tourist attractions often contact will turn bright black. That's the reason. There are agates that form "bloodshot", but the substance is constantly changing, and it is normal to add complex external influences (human contact, sweat, different constitutions).