Manually buffing the scratch with a wool polishing pad can remove scratches from glass; using an electric buffer on medium speed is also an option. Buffing is done with cerium oxide or jeweler's rouge. Manual buffing requires gentle motions and rubbing against the scratch to avoid breaking the glass.
Assessing the damage before buffing is the best course. If the fingernails do not touch the scratch, the problem can be remedied without professional help. Deeper scratches require professional assistance. Polishing by hand can be done on small surfaces, such as on an iPod or tablet screen. An electric buffer is more efficient than buffing by hand, but wear safety goggles. If the jeweler's rouge comes in solid form, holding it close to the pad on low speed is necessary. Smooth leftover abrasions with P1500 rubbing paper.
After buffing, cleaning the area with a one-half ounce of ammonia and 2 cups of water finishes the job. Wear gloves, a mask and goggles when using the chemical. Place the mixture in a spray bottle and apply it over the buffed surface. Use a lint-free cloth and paper towel when cleaning. Rebuffing is necessary if the scratch remains visible. Contact an expert if rebuffing does not remove the scratch.