I can figure out clothing and shoe sizing. One thing I never figured out were sunglasses. First of all, I'm sure higher-end, more expensive sunglasses equals higher quality frames, lenses, and fit. But honestly, knockoffs and occasionally even gas station sunglasses look incredibly similar. Maybe I just don't have the "eye" for sunglasses. Anyone want to explain to me the difference between a pair of Dior sunglasses versus a knockoff? Or just help me out in picking out glasses? Also, is there sizing to sunglasses?