Definitely an uncommon reference (9101) and in great condition, too. With vintage watches, condition and originality are everything so make sure that nothing gets altered (e.g. case polished, dial or hands re-lumed, crown replaced) if taken to a watchmaker. Though not at the very top of Longines' lineup in the mid-late 1950s (that would be the Conquest), this Goldengines with an 18K screw-back case would have been an expensive watch when new. Congratulations on a special heirloom and thanks for sharing the photos.