u/greeboXII

I have a brief encounter that I will be putting in front of my players, the mysterious npc will gift them with a glowing ember of coal that has been created by the cult attempting to free Asmodeus from the Nine hells, is there a way that I can work this item where detect magic or identity won’t reveal the curse? It ties into the broader campaign and will provide clues to the cult’s existence but I want them to figure it out through game play rather than a simple spell. I was thinking of having this being an item from the nine hells, would it being from a planar dimension prevent detect magic or identity?