The touch of Thanatos

You touch a creature that has been dead more than 1 minute before the cast. When the spell is cast ethereal light is drawn from the body bringing the deceased soul into a crystallized gem form that can be taken by the caster for transport to the afterlife.

If the deceased is resurrected while the stone is in possession of the caster it flashes away in a bright light alerting the caster of the resurrection.

Speak with dead allows the caster to communicate with the soul as if it was the corpse and the soul returns to the gem after this can only be done one time.

This spell does not allow the caster to manipulate the souls in anyway and these can not be traded or used as currency. To form soul coins from these, the spell must first dispelled.