Out of curiousity, does any know why the differciation between a 1912 patent Gem and 1912 patent Gem Junior? I don't see ANY difference between the two (the Junior's on the right). Also, is there any way to approximately date these?
I am not aware of any real difference.
Here is a theory.
GEM's earlier razors (1900/1901 patent date) were called "Gem Junior Bar". I think the "bar" referred to the mechanism that held the blade down -- a bar across the blade. They might have emphasized this aspect because earlier models didn't have that bar but instead had guides along the sides to hold the blade in place.
So, when the went t the 1912 model they may have dropped the "bar" leaving "GEM Junior". Perhaps later on they dropped the "Junior". I don't know where the "Junior" came from in the first place.
THE PICTURES:
The first attached picture shows a Gem Junior Bar (1900/1901) with the bar raised.
The second attached picture shows an earlier model (Pat Pend) before the bar was introduced. I pointed arrows at the two guides at the edges. This model was for wedge shaped blades. It does not say "Junior" on it. It just says "Gem Safety Razor".
The third attached picture shows another model (with the same 1900/1901 patent dates) that has guides allowing for flat SE blades. Just won this on eBay and haven't seen it in person yet. It also says "Gem Safety Razor".
I think that the small screw that I have pointed to in my photo allows this razor to be converted to either wedge or single edge blades. That little adjustment screw is also visible in the photo of your razor too.