India, which produces these stones, produces nilion[1] also, a stone that differs from the last in its dull, diminished lustre, which, when steadily looked upon, soon fades from the sight. Sudines says that it is to be found also in the Siberus, a river of Attica. In appearance it resembles a smoke-coloured topazos, or, in some cases, a topazos with a tint like honey. According to Juba, Æthiopia produces it, upon the shores of the river known to us as the Nilus; to which circumstance, he says, it owes its name.