Cross reference the Movement number with the case number to find the time scale of when your watch was produced.
The reason: There have been a lot of watch manufacturing companies that have come and gone over the years.
Many have gone out of business, while others destroyed records to save space.
Watchmakers like Gruen, however, destroyed their records, making exact dating impossible.
Use a case blade to pry open the snap-on case back of a pocket or wristwatch.
Some companies (as with the Gruen Watch Company), even lost rocords to fire or other natural disaster. I am sure they had no idea that their timepieces would someday be collected.
There are several ways to get an idea of when your watch was made.
The best way to identify the date of manufacture of a watch is to locate the serial number on the watch’s movement.
The movement is the spring-loaded mechanism the runs and regulates the timepiece.
Between 19, the watches may also feature 46, 47, 48 or 49 along with a symbol, signifying the manufacture year.