Waltham pocket watches are perhaps the easiest timepieces to date. The American Waltham Watch Company can trace its roots to 1849. Each timepiece has been engraved with a serial number since 1852, starting with number 50. The serial number will pinpoint the year of manufacture but not the exact date. Additionally, Waltham identified each pocket watch's model name on the movement. Serial numbers to date the watch are only found on movements. The number on the case provides no information.
Place the screw-down Waltham pocket watch face down in the palm of your hand. Locate the seam between the case back and case. Place your fingertips around the edge of the case back. Rotate the case back counterclockwise until the case back is free from the case.
Use a jar lid grip remover for stubborn screw-down case backs. Never force a case back. If the case back remains immobile, take the timepiece to an expert in pocket watch repair for removal.
Press the crown down on a hunting case Waltham pocket watch, which is a different model from the screw-down version. The depressed crown will release a latch that opens the front cover over the crystal. The depressed crown will also release case back cover. Once the latch is released, open the back cover by placing your fingernail or blunt blade between the back cover and case to pry it open.
Use a magnifying glass or jeweller's loupe to examine the movement. On one side of the movement is the Waltham name with the model name below it, such as "Santa Fe Route", "Silveroid", "American" or another name. On the other side of the movement is a series of numbers ranging from two to eight digits.
Record the number and compare it to the Waltham pocket watch serial number list posted on numerous online pocket watch sites. Expert pocket watch repairpersons and watchmakers also carry the list. If, for example, your Waltham pocket watch is engraved with a serial number between 10,200,000 and 11,099,999 it was manufactured in 1901. A Waltham pocket watch with a serial number 35,000,000 or greater was manufactured in 1957.
Reputable watch sellers will allow buyers to examine the movements and open the case back for inspection. When shopping for a Waltham pocket watch keep a copy of the serial number list for reference. The case back will only tell the buyer or owner the gold content of the case, such as "18k".
Avoid touching the movement with your fingers. Body oils and dirt could contaminate the movement.