I once had eyeglasses that used a then-new type of glass with a higher index of refraction which allowed the lenses to be thinner. (I'm very nearsighted and have to use a strong lens prescription.) That glass also had a rather high dispersion, so when I looked at a street-lamp through the outer part of the lens, near the edge, I saw a nice little spectrum. I could even make out spectrum lines in sodium and mercury vapor lamps!