Sorry, Ted, I've been researching (Jewish) genealogy (based) in Northern Germany for 30 years now, and I don't see a clue for Jewish ancestry just by interpreting the writing/symbols on the gravestones.
As Andreas states: it is custom in Germany to use the "asterisk" as a genealogical sign for the birthdate on tombstones. The surname "Blunck" is fairly common in Northern Germany and not necessarily Jewish.
None of these hints would solely be an indicator of Jewish ancestry. As I wrote privately: the only way to find out is the classical paperwork genealogy.
Corinna (Wöhrl), near-Hamburg, Germany