You're looking at Mohs hardness 9.0, Young's/Bulk/Shear moduli 345/240/145 (all GPa), 400MPa tensile strength. No glass is that strong.
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Ironically this makes your 2nd point much stronger, since I imagine actually milling/cutting/making adjustments to Sapphire is much harder.
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But honestly I think the main reason is even simpler: cost. Glass is cheap as hell.
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Replying to @bofh453 @whitequark
Glass lenses are actually rather expensive compared to CR39 which is almost as good (within 1.0 Abbe value diff) & better at blocking UV.
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Replying to @RichFelker @whitequark
Oh that's another issue with sapphire: uncoated, it passes down to 195nm (UVC) with almost zero attenuation.
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Replying to @bofh453 @RichFelker
so you'd need to wear glasses under your glasses. I fail to see the problem with this. Imagine the memes
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Replying to @whitequark @bofh453
The way I look at that, wrt UV, my eyes are still no worse off than people who don't need glasses.
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Replying to @RichFelker @bofh453
they wear sunglasses sometimes though and you'll need two glasses in that case, I mean
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this is a good argument for a photochromic coating
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Can't stand that without huge lenses that cover all around eyes. Otherwise with darkened lens, reflection of skin saturates dark areas.
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Looks like what you get with a max(x,0.25) filter applied to an image.
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