The means by which Akuma (and Infernals) gain Magical Material Bonuses
Akuma lose their magical material affinity when they become Infernal Exalts, breaking all existing attunements, while the Green Sun Princes weren't designed to have a magical material. Both types of Infernal Exalted can force the issue by paying double the mote cost as normal in order to gain the artifact’s material bonus or they can pay the normal cost to attune without the bonus.
Infernal relics cannot be crafted from Creation’s magical materials unless those materials have been tainted with vitriol, corrupting its substance into a degenerate form better fitted to the needs of the Infernal Exalted. Orichalcum takes on a brassy tinge flecked with the green of verdigris; moonsilver flows into alien forms emulating the shapes of the demon races; starmetal shimmers with the light of the dying Malfean stars; jade cracks and coarsens, its brilliant colors dulling to a noxious ocher; and soulsteel darkens with the Ebon Dragon’s twisting shadows. Baptizing the magical materials takes five days. To taint an artifact crafted from these materials, the character seeking to corrupt it must own and be attuned to it.
All Infernal Exalts may attune to tainted magical material artifacts as if they resonated with that material. Other Exalted treat tainted artifacts as made of the wrong material, even if they naturally resonate with the material in its pure state.