You can polish it out. Use a dual action sander with a thick cloth like a towel over the pad. Use coarse polishing compound on the frosted area. Go slightly beyond the area of concern. When the whole area looks the same (you can't tell any difference between the sandblasted area and the whole area you've been polishing) move to a finer compound and work a slightly larger area. When it's all the same use a very fine compound like jewler's rouge and repeat on an even larger area. The reason you keep working a larger area is you are removing glass and if you concentrate in one area you'll have a noticable magnafying glass effect in the spot. Good luck. Oh yes, change the cloth with each change in polish.

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