When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Make sure it is on the outside. I made an of myself with the same question only to find it was a smudge on the inside. If it is on the outside there are glass polishing kits at most auto parts stores that may do the job. Gotta be careful though as taking off too much glass in the process will lead to distortion.