A photopgraph featuring Soulstone
Soulstone is an incredibly rare kind of crystal found only on planet Earth which has the unique property of being capable of absorbing and emitting souls and soul energy. The mysterious sword of Dugal Cain is partially made of soulstone, allowing it to use the soulstone's unique properties. Because of the scarcity of the crystal, Rome uses synthesized soulstone for their Neostigma weapons, of which the quality is undoubtedly much lower than that of the original.