Here is the fake, note the location of the center pin on the scale is not in the center. Russell factory staff told me the handle is a Camillus.




Here is a Camillus catalog photo, note the location of the center pin on the handle matches the position of the pin on the above knife

next here is a knife that belongs to Pertinux, posted on photo bucket. I have copied the photos to my library, but they are her photos. This knife has been certified as a genuine 1933-1941 curved tang stamp knife, by the Russell factory.



here is an earlier Russell Barlow with straight line tang stamp, that Bernard Levine told me was probably genuine




And here is a Russell Commemorative with Delrin scales. It is a modern knife, not an original Russell from 1875 to 1941.






So far I have learned that before 1933 Russell used straight tang stamps, after 1933, until 1941, they used the curved tang stamp. The fakes, German replicas, and commemoratives, all use curved tang stamps.
There are several features of Small Russell Barlows that I am learning to distinguish.
1. The location of the center pin on the handle should be in the middle of the scale, not closer to the bolster. However, commemoratives have centered pins, as do some 1967-1971 German replicas.
2. The pins should be steel, not brass
3. The bolster on an original Small Russell Barlow is Iron, not nickel silver.
4. The ring on the base of the original Small Russell Barlow is close to the handle scale, on commemoratives there is a wider space. Also the Arrow head on an original Russell has more space before the pivot end of the bolster, the commemoratives arrow head on the bolster is closer to the top of the bolster.
5. The blades on an original Small Russell Barlow should look old, pitted, have patina, if the blade is shiny and new looking, it is suspect.
6. The color of the bone on Small Russell Barlows varies from yellow and smooth, to brown and saw cut. The colors were not specific to pre or post 1933, though the pre 1933 are often yellow and smooth, that may be just from wear.
7. Original Russell's have the pivot pin past the tip, and to the side of the Arrow head on the bolster.
disclaimer, I am just learning, and sharing what I think Ive learned. I am not an expert, and any opinion I give is just that. I do try to verify what I think is true with multiple sources, so hopefully the information is useful and accurate for others to consider.
Please feel free to add any photos of Russell Barlows you own or are interested in. And please add any knowledge you have about identifying Russell Barlows.
(edited to add info about German replicas, exclusive use of iron bolsters specific to Small Russell Barlows, and bone colors, provided by Miller Bro's below)