Bought a pair of ie900 on Amazon 3rd party seller and turned out it's fake, by referencing
https://www.audioreviews.org/sennheiser-counterfeits-fakes/, plus noticing that there was no signature, and the QR code on the box doesn't match the number on the cloth bag's metal tag.
Later on, bought from another 3rd party seller with many good reviews, and that pair was genuine (produced in Ireland, No. 20000+)
So, be careful when buying from Amazon 3rd party sellers. I've taken some photos for both and it anyone is interested I'll try to upload them (cannot find a way to upload images so far)