Thanks everyone! I'd LOVE to go shopping with anyone willing to tag along! Wouldn't that be fun? :o) I have a whole set of the purple glasses (I think 6 of them.) And lots more of the little red cups. I'm almost afraid to use them ~ I thought they'd look nice with tea lights in them at Christmas...hmmm? Oh, and the 6 sided red one is an old AVON bottle. I think it's missing it's top, maybe it had cologne in it or something?

It may not be a stain from minerals but etched watermarks from a cleaner containing a fluoride compound of some sort usually found in metal cleaners. Vinegar will not do what you have and I would speculate the cleaning lady used something else with the ability to etch glass such as a stainless steel cleaner or diluted drain cleaner. If nothing else works I would suggest trying Duragloss Nu-glass #755 and can be found in most auto part stores. It is formulated to remove etched watermarks from glass but requires a lot of elbow work or a buffing attachment on a power tool.

go to a glass store have them cut you glass otherwise get a different fixture, your going to spend more "trying" then that fixture cost. im also not following how you"see" the light bulb in this fixture.

@Mary Elizabeth I also want to say that I dislike Renewal by Andersen that you are talking to. And I actually do like Andersen windows. But Renewal by Andersen is different. Andersen windows (not Renewal) are sold via an Andersen network of authorized dealers. Renewal by Andersen are franchise operations with no real oversight by Andersen, and they also do not offer the full line of Andersen windows available. Renewal by Andersen franchises tend to hard sell, they often come to the house and monopolize you with a pitch for 3 hours to wear you down, and they often do the trick of "buy right now and we will give you an enormous discount that will not be available after today". Please keep looking for better windows contractors than Renewal by Andersen. Your area should have a good selection. There is even a frequent poster on this site, @todd, who is a windows contractor in Minneapolis (though I have no knowledge of him, just seen him post on here often).