Tech wise nograin is considered being various.
From what i do know "various" does not include - standard metals [iron, mithril and upper ones], wood, leather, cloth, gold, stone and probably something else i missed [edit: glass and crystal most certainly]. It does include some other metals like strange metal girdles, brass rings, girdles of greed [presumably copper, i think], pearls, corals [2s necklaces].
Given how game sometimes uses anagrams I did rolled nograin through transmutation looking up variations which sounded reasonable. Best i ever saw was girlish Norwegian name, but, well again, my English was never top level to start with.
Personally i believe it being anagram of "no angry" but that is rather stretched version.
So far rolled 15 casters with RoDS and shamelessly killed them within 200 turns. For eternium glory!
(after 15 I stopped counting...)