50 rubles addendum
No genuine in hand for direct comparison. The forgery here shows its shape of the front of the helmet and the tiny crook in the attachment of the bayonet without shading. In both genuine and forgery, the bayonet is placed so the soldier would shoot his bayonet.
25000 rublesThe characteristics are the same for both colors.

Genuine. The top of the left circle with the hammer and sickle has a 3mm line above (A&T). It is a thickening of the top part of the circle, possibly a retouch; compare with the same design element on the right side. The curl at upper left is more complete than the forgery (Barefoot). This is true of some but not all forgeries. Note the shape of the "clouds" at upper right; this is found on some forgeries also. Not indicated is the column at right has 2 lines that are just short of the curved ornament above plus 2 distinct lines that do touch the curved ornament. The fineness of the impression shows this to be a relatively early printing.

Forgery. The top of the left circle may be slightly thicker but is not like the genuine. The curl in the upper left ornament could be more closed or short like this. This forgery has "clouds" like the genuine. A key is that in the right column, there are 2 lines that are shorter and more crooked than the original. Plus the other 2 lines more or less merge into one when they reach the circular ornament above.

Forgery. The whole circle at upper left has a thicker outer line; compare with the circle at upper right. The curl in the left circular ornament is short. The "clouds" are larger and very different from the original. The 2 leftmost lines in the right column are short like the forgery above. Also noted is the shading outside overall and outside the frameline, an artifact of the photo film used for copying. There are genuine with a hairline outside the frameline but not as heavy as this.

Forgery. There is no heavier line/possible retouch in the upper left circle. The curl is short. The "clouds" are different. The lines in the right column are like those of the forgery first described. There are dots and blobs outside the frameline that are characteristic of photographic copying.
Genuine brown olive imperfs are scarcer than blue imperfs. The genuine brown olive perfed stamp is rare.
ImpressionSome genuine earlier prints have been shown in this thread: fine framelines, very sharp details. The genuine can also run to slightly grainy prints typical of litho printing to rather murky prints.
Forgeries run from slightly grainy prints to very murky. Some have lines of dots and blobs outside the framelines characteristic of sloppy photographic copying.
Additionally, sheets of both genuine and forgeries have been recorded but are different sizes/formats. Blocks of both exist and are not rare.
Papers and gum
Find the genuine stamps here! The genuine and what I would call the first forgery are so similar as to be indistinguishable. Add in the effects of time, too. Barefoot states the forgery gum is greenish, but I find the the
paper of genuine and the first forgery are greenish under certain types of light. The papers of both are thin so the design shows through to the back against a black background. The weave is only slightly apparent when held to the light.
The gum is thin, cream to yellowish and semigloss on fresh genuine stamps. Again, with time, it can go to brownish and shiny as it does for the first forgeries. For the scan above, the first and third are genuine, the upper right stamp is a first forgery.
Perforations tend to be clean for genuine, clean to rather rough for forgeries.

These two are from what I call the second forgery. The paper is thicker, cream-colored, smooth-surfaced on the face. The gum is thin and cream to yellowish, though like the left stamp here, they do exist without gum and look like they were never gummed. "G.S." is an owner's mark and not a expert mark.
The
soft bright white paper forgery mentioned in earlier posts is the most recent of the forgeries I've encountered and was probably not seen by the real experts (A&T). For a view of a back, see rod's scan 3 posts back. The paper has a wider weave than the genuine, but is most notable for being so bright as to be bluish, an indication of optical brighteners typical of recent papers. The impression is moderately grainy and rough with dots and blobs outside the margins typical of sloppy photographic copying. This forgery is dangerous in that it has some corrected design elements but looks to be copied from forgeries; so the forger had some idea of what genuine stamps look like.
For online studies of the later surcharged stamps see:
https://stampsofarmenia.com/Big Blue has forgery info of this and other issues of Armenia:
http://bigblue1840-1940.blogspot.com/Thanks again to rod222, a generous stalwart of SCF.