Postage Due - 1930 Or 1931?

I am still very new to stamps and have what is likely a very simple question but I don't know the answer. Here are images of a set of Postage Due Stamps but I don't know how to identify 1930 vs. 1931 stamps. Any help is appreciated.

You'll need to use a perforation gauge to tell for sure. If your stamps are from the 1930 series they will be perf. 11 all around; if from the 1931 series, the perforations will measure 11 x 10.5.

These are tough ones. I've been sorting and doing album pages for these for a while. The colour variations are killers. But basically the difference between the two years comes down to perforations. The 1930 issue is perf 11 (both vertical and horizontal) while the 1931 issue is perf 11x 10.5. Both are unwatermarked.
Then of course there are colours, carmine, scarlet, dull carmine. That's where it gets tricky.

Now I am really confused... the 50 cent appears to have 11 and 12 perforations. I'm guessing the 11/12 as I count it means these must be 1931's.

If you are just counting perforations, without the aid of a perforation guage, you need to count only the number of perforations in a 2 centimeter distance to arrive at the proper measurement.

To me, your 50 cent stamp looks like it is perf 11 X 10.5.

Steve

Steve is correct about the 50c stamp. Through the magic of photoshop we can compare the top and side perfs and see they are not the same.



Therefore it is 1931 issue.

Thank you. Now I understand.