Regarding the crystal issue...
The “non distortion” crystal is not fragile at all. The crystal of PAM569 and Pam389 for instance, has no distortion and it is 5mm thick!
The issue about the crystal with distortion (lenses effect) is not only the distortion itself, it is also about reflection. It shows you the reflection of the outside and the reflection from the inside of the cristal, making two reflections that comes through opposite sides, wich make dial illegible sometimes.
The crystal without lenses effect (the correct one for new panerai releases) has only ONE reflection, from the outside of the crystal.
Also, the non lenses effect crystal gives the dial a more deep look wich looking from an angle, you can see the “rehaut”, where on the distortioned crystal you see the dial closer to the bezel.
I hope I could make myself explained. It is not only about distortion.
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