Materials that are important and can be reused, can only be worn on a wound if they actually heal or help protect the wound from being infected.

Chapter 301 Section 23

An ornament that is permanently attached to a garment, such that it cannot be taken off, can be worn outside. Something which has little importance, meaning that if it fell off you would not bother to pick it up, it is permitted to be worn even if it is simply attached.

Chapter 301 Section 24

Herbs hung around your neck for a refuah are permitted.