The stem is the tiny knob that you use to change the time on your watch. Removing it takes few steps, but they are steps that require precision, care and patience. Though quartz movement watches aren't as complex and delicate as mechanical watches, they can still be damaged, especially when you remove the back of the watch and expose the movement itself.
Open the case back. Use only the right kind of opener for your watch. Otherwise, you may scratch the watch back. If your case has slots, use a JAXA Universal Case Opener, a Meikosha 19400, or a Bergeon 5338-1 F. For cases with grooves, such as Rolex, use a Bergeon 5537. These are all handheld case-back openers. A professional case-back opener, the Bergeon 5700Z, sits on the workbench of nearly every watchmaker in the country and runs about £227.50. Needless to say, buy a handheld or pocket case opener unless you make a living fixing quartz-movement watches. For snap-on cases, the Bergeon tool will work. Whatever kind of case you have--snap-on or screw-on--use only the right tool for your watch Otherwise, you will scratch the case.
Grip the case tightly in your hand, in a vice or in a case crab.
Screw open the case using the screwdriver or, if the case is snap-on, pry it open by finding the grooves or slots on the side of the case. Remove the watch cover and place it aside.
Locate the stem push-button. In many Japanese watches, the push-button is labelled. Push it down about half a millimetre with the screwdriver or your thumb, and with your other hand pull out the stem. If the watch doesn't have a push-button, it will have a screw lever. The screw lever is spring-loaded and holds the stem to the crown in order to set the time and date. Turn the screw lever one to one and a half times and pull out the stem.
Keep Rodico, a waxlike cleaning substance, around to clean off the fingerprints you leave on the watch cover.
For screw-lever watches, do not turn the lever more then one and a half times. Doing so will disconnect the lever from the lever setting, and to put it and the stem back on, you'll have to disassemble the dial and hands, a painstaking ordeal.