The two case numbers listed on any Rolex watch case or watch certificate are the reference number, which tells you what type of Rolex it is, and the serial number, which tells you when your Rolex was made. These numbers are necessary to know if your Rolex is being serviced or if you want to guarantee that your watch is a genuine Rolex and not a counterfeit.
Find the reference number and the serial number on your Rolex watch certificate. If you do not have a certificate, you can remove the watch bracelet and find both numbers. There are two types of Rolex watch case lugs. The first type has the springbar on the outside of the lugs. The lugs are on both ends of the watch case, and the ends of the bracelet are inserted between them. You can see a small circle on each side of every lug if your case has the first type of lug style. The second type has the springbar underneath the end of the bracelet. Turn the watch over to see the springbar where the bracelet meets the watch case.
Press down with your thumb on the bracelet link nearest to the watch case or the part of the bracelet between the lugs if you have the first style of lugs mentioned in Step 1. If you have the second style, turn the watch face down and press down on the part of the bracelet that meets the watch case. In both cases, you are pressing down on the same area of the watch bracelet, just different sides of it. While pressing down, place the end of the springbar tool on one end of the springbar. Press the springbar inward until it releases, which means it will not spring back out to its original position. Repeat on the other side of the springbar. Then perform the same task on the other side of the watch.
Pull both ends of the bracelet out from the lugs. On the watch case between the lugs you will see numbers. Nearest the 12 o'clock position is the reference number, and nearest the 6 o'clock position is the serial number.
Go to the Oysterworld website for a list of all Rolex reference and serial numbers. Here you will be able to find when your watch was made and what type of watch it is. On the webpage, click on "Production Dates by Serial No." and "The Referenzes."