Often, you can find online serial number databases that will help you narrow down the age of your watch to the year it was manufactured, or thereabouts.
See if there's a free online database of serial numbers from the company
When it doubt about which is which, see the note below regarding online databases. The model number may be referred to as the "style number" or "reference number," while the serial number may be listed without any sort of qualifier. You may be able to save yourself some detective work if you have your watch's papers, such as the warranty, receipt, etc. But just where is this number located? Unfortunately, it sort of depends on the watch, but here are some tips to tracking it down: If you have paperwork from the watch, the serial and reference numbers should be there The watch's serial number can, in many cases, help you track down this information in conjunction with online or company-owned databases. A vintage Longines watch featuring the watch serial number and model on the inside of the watch case.Let's say you buy a pre-owned or vintage watch and want some more information on when it was made, what it might be worth, etc. Open the case back some watches include the serial number on them. Is your watch a modern model with a sapphire case back so you can see the movement from the back? It may be difficult to tell the serial number apart if it’s engraved on the movement from the back of the case, but it’s worth looking around, especially if you have a magnifying glass. If the watch has a transparent case back, look at the movement Again, if in doubt, plug the two numbers into Google with the word “ Rolex,” and you will be able to tell which one is the model number and which is serial, depending on the search results. Model numbers are generally four, five, or six digits long, while serial numbers can be up to eight digits long. Take off your strap, and you will see it right away. Rolex places their model and a serial number between the lugs of the watch. If the watch is a Rolex, check between its lugs. When in doubt, do an internet search for each number and the name of the watch company and see what comes up. However, you will have to learn to differentiate between a serial number and a reference number, a model number. The watch serial number may be on the back of the case, especially for modern watches. You email them the number from your watch and some pictures and then wait for a response. Longines offers this service free of charge for all of its watches. Oftentimes, you can find serial number databases online that will help you figure out the year your watch was made. See if there is an online database of company serial numbers If in doubt about which one, see the note below about online databases. A model number can be referred to as a “reference number,” while the serial number may be listed without any qualifications. You might save yourself some effort if you have documents of your watch, such as warranties, receipts, etc. If you have documents from the watch, the serial numbers should be there But where is this number? It depends on each watch, but here are a few tips for finding one. If you just purchased a pre-owned or antique watch and want more information about it, the watch’s serial number can help you trace the company-owned database information of the watch.