The forgeries of the stamps of the Erivan pictorial issue are normally not too hard to detect, but sometimes, one slips through. Happened on page 184.
The giveaway is the broken socket of the stone in the lower right corner. Of course the overprint cant be genuine, if the basic stamps is a forgery.
Unfortunately many illustrations of the early stamps of Armenia in this ARTAR catalogue are of forgeries and thus this part of the catalogue is NOT reliable. On the other hand the bulk of the catalogue on the Soviet issues is excellent and a reliable source of data for which he is to be congratulated.