Atomically　precise　low-nuclearity　(n8]6+　AgNC　stabilized　by　six　highly　negative　[LiNb27O75]14−　polyoxoanions.　This　marks　the　first　PONb-protected　superatomic　AgNC,　designated　as　{Ag8@(LiNb27O75)6}　(Ag8@Nb162),　with　an　aesthetically　spherical　core–shell　structure.　The　crystalline　Ag8@Nb162　is　stable　under　ambient　conditions,　What＇s　more,　it　is　water-soluble　and　able　to　maintain　its　molecular　cluster　structure　intact　in　water.　Further,　the　stable　small　[Ag8]6+　AgNC　has　interesting　temperature-　and　pH-dependent　reversible　fluorescence　response,　based　on　which　a　multiple　optical　encryption　mode　for　anti-counterfeit　technology　was　demonstrated.　This　work　offers　a　promising　avenue　for　the　synthesis　of　fascinating　and　stable　PONb-protected　AgNCs　and　sheds　light　on　the　development　of　new-type　optical　functional　materials.　©　2024　Wiley-VCH　GmbH.