Yes, that is normal. Precious resin is Montblanc's name for a high-grade acrylic, in material terms a close relative of Perspex. Shine a strong light on a black body and it becomes translucent, showing a reddish to red-brown glow. Collectors treat the effect as an indication of authenticity if anything, since many fakes are made of opaque plastic.
On the Meisterstück 164 ballpoint the cap inscription “Montblanc Meisterstück Pix” is likewise part of the original. Pix is an old registered house name that Montblanc uses on ballpoints and propelling pencils in the Meisterstück range, not an invented term. The serial number on the clip, by contrast, can only be read at the factory: from it Montblanc can tell the year of manufacture among other things, but without the key it means nothing to a collector.
Binding confirmation of authenticity comes from Montblanc alone; the pen has to be sent in, and the service is chargeable. Any judgement made from photographs remains an opinion, even though clean engravings, the fit of the original refill and the behaviour of the material already provide strong pointers.