Yes, To your question! The WwII era vision blocs were Clear And appeared Greenish. To the outside viewers!
Newer optics.... Some are coated with laser reflective coatings.... Ranging in colors. Mostly Redish in color!
If you do WWII. Mostly? I would stick with green!
My small video deals mainly with optics you can slip a film behind! Some will still need to be painted by hand!
And as the one shown above.... Is really well done!
Hope all of this answered somewhat your question?