If you can insert a fingernail into a scratch in glass, it's probably too deep to fix [source: Ultimate Handyman]. However, if the scratch isn't too deep, you can try minimizing or eliminating it from the glass as follows.

What you'll need:

  • Cerium oxide (i.e., jeweler's rouge -- available in most jewelry or craft stores) or whitening toothpaste -- not gel
  • Electric buffer with polishing pad (preferably lamb's wool)
  • 2 cups (1/4 liter) warm water
  • ½ ounce (14.8 cubic centimeters) ammonia
  • Spray bottle
  • Paper towel
  • Dust mask
  • Safety goggles
  • Rubber gloves

Here's what to do:

  1. Lay the glass on a flat surface if you can.
  2. Apply a little bit of jeweler's rouge or toothpaste to the pad of your buffer.
  3. Put on the mask and goggles, and buff the scratch at low to medium speed with the electric buffer. You can also try buffing the scratch by hand with the polishing pad. Don't apply too much pressure.
  4. While still wearing your protective gear, fill the spray bottle with 2 cups (of warm water and 1/2 ounce (14.8 cubic centimeters) of ammonia.
  5. Spray the area you buffed and wipe it clean with a paper towel.

Please note the following:

  • You can repeat this process several times, but if it doesn't work, chances are you'll need a professional to remove the scratches. Some scratches simply can't be removed.
  • You can easily distort or break glass while trying to remove a scratch. Therefore, it's best to lay the glass on a flat surface while you work on it. If this isn't possible, you may want to call a professional rather than risk distorting or breaking the glass.
  • [source: How To Clean Stuff]
  • You can leave a noticeably shiny patch when polishing a scratch. Therefore this method is best for small surfaces like a watch crystal.
  • You might be tempted to use an abrasive paper, like sandpaper, to try to remove a scratch. However, this will leave an opaque patch that will look worse than the scratch.
  • [source: Ultimate Handyman]