Watch crystals take more abuse than any other part of a watch. The crystal is exposed and can be scratched or smudged due to the number of objects that come into contact with it throughout the day. Some watch crystals are made of glass, while others are made of plastic or even synthetic sapphire crystal. Keeping the watch crystal clean can ensure your watch looks new even after many years of wearing it. Keeping a watch crystal clean is very easy and inexpensive.
Snap the watch case open. If you own a specialty watch, consult the directions on how to properly do this so you do not break the watch. Many watches can be opened up by simply inserting the flat edge of a screwdriver into the edge of the casing and snapping the case open.
Pop the crystal out of the case. This must be done very gently to avoid damaging the crystal. Gently, but firmly, press the crystal from the inside while holding onto the edge of the casing. It may take some time, but eventually the crystal will pop free from the case.
Pour some brass cleaner on a clean rag and polish the crystal. Brass polish has a mild abrasive in it, so it will buff out light scratches found on the crystal. Continue buffing the surface of the crystal with a clean, dry cloth until no trace of the polish remains.
Remove any dirt and debris from the edges of the crystal, using either a Q-tip or the edge of a clean cloth. If the debris is stubborn, dip the Q-tip or cloth in soapy water and use it to remove the debris. Allow the crystal and the case to dry completely.
Apply a small amount of crystal cement to the edges of the watch crystal and gently set it back into the case. Allow plenty of time for the cement to dry completely before putting the watch back together.