First Referenced:
Our Final Acts (Part 6)
The Amethyst Suicide Device is a small pyramid shaped crystalline device, originating from the Gemstone Hegemony. Its purpose is to serve as an instant painless means of suicide, completely obliterating the body of the user. It is activated through direct physical pressure from the user.
One such device was used by Conn Thompson, to prevent the Preacher from taking his body and soul, and also to avoid a painful death from radiation poisoning.