Bulova 1964 Prince

I recently bought a group of 6 watches advertised as "I inherited these, hope somebody can use them, don't know if they work". $2.30 each, 5 were quartz, and this one. One turn of the crown and it took off and is keeping time. It is white gold plate on a white gold plate band that is expansion in the middle and mesh on the ends. Face is a dark slate with white gold indices and a sub-second dial.

After considerable searching, I believe this is one we haven't seen before. The ad is dated 1965. The ad combined with the line book entry seems to indicate this is a 1964 Prince "B".

It has the number 2533 stamped on the inside of the back that I assume is the case number and the equivalent of an ink stamp in newer watches?