I very pleasantly stumbled into the webpage of The Perfin Society
“Perfin? What exactly is a Perfin?” you’ll ask. The best way forward is to go through the definition provided by the society itself.
As I mostly blog on philatelic musings with a connection to India, the very site of The Perfin Society came as a delightful surprise for me. The society has uploaded, for the benefit of collectors at large, a comprehensive (yet work in progress) listing of the The Perfin Stamps of India. This builds on the work of the late Magnus Werner, covering all perfins on Indian postage and revenue stamps and postal stationery, including Indian States, Pakistan and Burma. The current edition has been updated by Jeff Turnbull, a note of appreciation from my side Jeff! Fantastic work!
Finally, a ready reference to decipher that unusual perfin marking on your stamps or covers. Another tool in the proverbial box of an inquisitive philatelist.
Link to India Catalogues>> The Perfins of India
Link to Society Homepage (I highly recommend joining it) >> The Perfin Society