Count: 0. No Italian last names that start with J meet the criteria when checked against authoritative Italian surname sources. This query is country-specific to Italy; interestingly, J appears historically only as an orthographic variant of I in old Italian documents and does not function as a native initial letter for traditional Italian family names.

Explain why this returns no results. The modern Italian alphabet treats J as a foreign letter and most native Italian surnames use I or Gi to represent the sounds English associates with J. Consult authoritative sources such as the ISTAT surname database, major Italian phone directories, archival records, and etymological dictionaries and you will find virtually no native-J entries. Where a J does occur, it most often reflects immigrant surnames, Germanic names from regions like South Tyrol, or archaic spelling in historical manuscripts rather than standard Italian surname formation.

Offer alternatives and guidance. Focus your A–Z index on letters that yield substantive Italian entries — especially Gi- and I- initials, regional variants, and historically common forms — and document exceptions clearly. Note that rare J-initial names exist as immigrant or regional cases, and include a short explanatory note in the J entry explaining why Count: 0 and pointing readers to close matches and reliable sources (ISTAT, phone books, archival records, etymological dictionaries, and reputable genealogy sites).