@captione Well..there are limitations to how the counterfeiters progress with creating exacting duplicates..in most cases they would fail, as the mould, presses and audio hardware are difficult to replicate as they are in the million $ value in R&D alone..so the fakes & authenticity thus are easily figured out on H/W variations and Codes/Model Types throughout the years from consumers..
And ironically, audio is subjective..I have a few friends who were also unable to decern which are the fakes or even the authentic, which they said were fakes too
But nonetheless the physical aspects and the knowledge based acquired through the history of the series ( about 8 years) are means to an end and final assessments for the golden grail of Sony earphones
Edit/
@captione I believe that "someone" could also be at Sony, as the rare and discontinued TYPE: AG-0503 Mfg in 2013 is a Relic and no longer even talked about for a long time and unable to buy in any retail Sony Box package today