nanodiamondEnglishOxford New American Dictionarynanodiamond /ˈnanōˌdī(ə)mənd, ˈnænoʊˌdaɪ(ə)mənd / ▸ noun a diamond particle with dimensions of only a few nanometers: you can't actually see them, because at roughly five nanometers long, nanodiamonds are invisible to the naked eye.