1926 Geraldine
Nice Geraldine Jabs. The Geraldine together with the Muriel were the first models with this particular shape and were introduced in an ad of 1926. I have never seen a Muriel for real, but the Geraldine once in a while pops up. The last ad we have of the Geraldine is from June 1927. After that the watch got a new name, Roberta, and is advertised with the Roberta name until 1929.
But the true specialty of this watch Jabs, is the movement. I have never seen this one. You would ask yourself, "what is this Alex talking about, it is just a 5P, isn't it? ". Well, it is stamped 5P, but the bridge lay-out is like its predecessors 5PPI and 5PP that ran until 1924. Yet, this movement seems to be from 1926. Although the movement does not have a date code, the serial number DOES place it in 1926. And it doesn't stop here: the place where "Bulova Watch Co." is stamped is also unique. Never seen that in 5P's. Normally it is stamped above the rachet wheel. So, a true mystery movement! Maybe Reverend Rob can say more about the movement. For more detail see also my PDF as published in the research forum: https://drive.google.com/file/d/0B1mKgMZb4oRQZlZCNkdsb2tycmc/view