Hello Fellow IWC Fans,
If you counted all the hours that I have spent looking at the 5250 series of watches, well it would be a lot of time. Sometimes it helps to get a fresh pair of eyes to point out the obvious but was overlooked by yours truly. In this case, my wife pointed out that the moon phase display windows are different sizes. Also, the moon phase disks are different sizes too. There are some other differences between these two watches such as where the serial and caliber reference are located. Based on a quick scan of other watches on the internet, this serial and caliber number placement seem to be random.
Perhaps everyone knows this but thought I would share anyway. I drew a circle to approximate the larger moon phase size (from the pocket watch) and then pasted it on the wrist watch to give you a better idea of the size difference. The circle is not perfectly aligned with the moonphase window (I am working with PowerPoint as my image editor). Also, the circles imposed on each watch are the same size. I also included the unedited photo.
Regards, George