Retainer Osco, we are thankful for the information. The manlings they met in the forest must have had something to do with this. Do they recall their names?
As for the gemstone...
Banning the stone would probably not work. It is used in many other things and is midly common. This would indeed require a vote from a council.
It is a council can decide not to bad the gemstones and do nothing of it.
They can monitor those with large quantity so they are not used in the foul creation of undeath.
They can issue a limit on the numbers owned.
They can ban the use temporarily until a situation is resolved.
They can ban it completely.
If they seek to limit or ban, merchant can seek out similar gemstones to replace their stock. We suggest jet, obsidian or the common black tourmaline.
Nan