A reliable authenticity check via the serial number is only possible by Montblanc itself, since only the manufacturer can interpret the coding. Especially with StarWalker ballpoints, the counterfeits are often very well made, which is why increased caution is advised. If identical serial numbers already turn up on the internet in connection with counterfeits, that is a clear warning sign; with the number mentioned that was not the case, which is at least not a bad sign.