Thousands of manufacturers have produced billions of pocket and wristwatches since people started carrying portable timepieces sometime in the 1500s. To make watch identification even more difficult, the same watch might have a case and timekeeping mechanism manufactured by different companies. Identifying the watch manufacturer or finding a serial number often requires opening the case, which can be challenging.
Examine the basic construction of your pocket watch. A watch with a cover over the face is known as a hunting case pocket watch; a watch with no cover over the face is said to have an open face.
Turn the watch on its side and look for a lip or notch in the seam of the back cover. Carefully try to pry the back cover open, but do not force it. If it doesn't pry open easily, try to open it by unscrewing it. If neither method works, take the watch to a professional.
Look for another hinged cover underneath the back cover. This is called the cuvette, and it is the back cover of the watch mechanism itself. If the watch was a gift, the cuvette may contain an inscription.
Open the hinged cuvette gently. If it resists, don't force it but instead take the watch to a professional. Do not apply lubricant to a stubborn watch case, as it may damage the case or the watch mechanism.
Search for an inscription on the inside of the back cover and the inside of the cuvette. This is where many manufacturers noted what type of metal the case was made of, typically either nickel, silver, gold filled or solid gold. A serial number might also be inscribed here, but that is the serial number of the case, not the watch itself.
Look for inscribed markings on the back of the watch mechanism, under the cuvette. This is where many manufacturers inscribed the name and location of the factory that produced the watch.
Locate a raised lip or indention on the back of the watch. This indicates a snap back case, which can be opened with a dull tool (not a knife) or a fingernail.
Insert a dull tool or fingernail into the lip and open the case. A special tool called a case knife is created just for this purpose --- it is thin enough to pry the back off, but not sharp enough to damage the case or cut your hand.
Notice whether the back case has six notches around the edge. This indicates a screw back case, which can only be opened with a special adjustable case wrench. Adjust the wrench so it fits snugly into three of the notches and turn counterclockwise to open.
Avoid trying to open a back with no obvious access point. This might indicate an "open through crystal" watch, which has a one-piece case and can only be opened from the front using a special tool called a crystal lift. This tool has tiny fingers that grab the crystal and lift it out of the case.
Locate a hinge on one side of the back. This indicates a "swing-out" case, which was popular in watches manufactured in the 1920s. Pry open the case and let it swing open from the hinge.
Look for the manufacturer's name on the face or back of the watch, or on the inside mechanism. Most wristwatches and pocket watches have a brand name or model name somewhere on the watch.
Open the watch using techniques described above and look for a serial number on the watch mechanism. Serial numbers on the inside or outside of the case provide information about the case, not the watch itself. Only the serial number on the mechanism provides information about the watch, and this information can be used to date the watch.
Research the manufacturer to find the meaning of the serial number. Some manufacturers, such as Bulova, have unique identifiers in their serial numbers. For example, beginning in the 1950s, Bulova began using a combination of letters and numbers to indicate the year of manufacture; an L stood for 1950, so L5 means the watch was made in 1955.
Evaluate the general style of the watch; even without a specific date of manufacture, you should be able to determine the decade or era when the watch was made. Watches from the 1920s were often ornate in an Art Deco style; in the 1930s they used smoother lines, and round movements became more common; by the 1950s, watch makers were experimenting with unusual shapes; in the 1960s, round was again in fashion and dials were generally larger; and in the 1970s many watch faces did away with numerals entirely as the watches became more flashy and metal bands replaced leather and cloth.
The National Association of Watch & Clock Collectors offers an appraisal course that teaches how to identify types of watches and their components; watch makers and trade names; and condition and authenticity of antique watches.