I have a T205 Phillippe Pied. 25 with a dark-blue collar, and I noticed that the blue ink on the back of this card seems deeper to me than the blue ink on the light-collar ones that I see on eBay. Front and back pics below. Could it be that the light-collar Pied. 25s have lighter blue ink all around than the dark-collar Pied. 25s?
Front of T205 Phillippe Pied. 25 with a dark-blue collar:
Back of the same card:
Back of a light-collar Pied. 25 taken from eBay:
It's not the best comparison since mine is a photo and the eBay one I assume is a scan, but the card I've got definitely has a deep blue ink on the back rather than a lighter-blue ink.