this watch...both the dial style and the chronometer rating are from later. I'd place the watch in the early to mid sixties. Yes a 1500...with either the 1560 or 1570 movement...and often the 1560 movements received 1570 parts in later services. Thoug not a rare or coveted model, because of the personal history the watch becomes irreplaceable. I'd give it a full service and enjoy wearing it for another 20 or so years.