How do I remove the scratches from an acrylic crystal?
Good old-fashioned toothpaste is a good start. Start by buffing a little bit onto a clean cloth over the area of the scratch. Rub lightly, and rinse with a very slightly damp cloth. Repeat until gone.
Note that there are also purpose-made polishes for this purpose, such as PolyWatch or Crystal-Kleer that can work quite well for many scratches.
If you have a watch made by Junghans (including Max Bill), please be aware that these crystals use a special coating called Sicralan to harden the crystal. It is not recommended to use PolyWatch or other abrasive products on these crystals.
(used with permission of TimeZone)