"The Great Sinner" is a 1949 film set around 1860 at the Wiesbaden casino in Germany.
Gregory Peck meets Ava Gardner and she introduces him to gambling.
"The Great Sinner" - Gregory Peck
At one point he puts two coins on the roulette table:
"The Great Sinner" - Coins on the table
The coin showing is a Germany Prussia Vereinsthaler of King Friedrich Wilhelm IV minted 1857 to 1861.
Another scene with a vereinsthaler obverse and three coin reverses:
The coin reverses shown are not the reverses of vereinsthalers but are reverses of German States post 1871 unification 3 mark coins.
Naturally, I just had to get a Vereinsthaler:
Germany Prussia Vereinsthaler 1860
Silver, 34 mm, 18.52 gm, Berlin mint 'A'
Obverse: FRIEDR. WILHELM IV KOENIG V. PREUSSEN
Reverse: EIN VEREINSTHALER XXX EIN PFUND FEIN 1860
The film does not explicitly state what "great sin" Gregory Peck has committed but could he have killed a ...