Surprisingly, sunglasses in some form or another existed in pre-historic times. Craftsman would take ivory and would carve glasses with two narrow slits in the middle of both lenses which would limit the amount of sunlight exposed to the eye. The 1900s served as the revolution of sunglasses with the help of movie stars like Audrey Hepburn in Breakfast at Tiffany's wearing Oliver Goldsmith's "Manhattan" and Steve McQueen wearing various Persol's throughout his career. This connection with movie stars and sunglasses continues to this day with many movie stars, such as Ryan Gosling, Christian Bale, Daniel Craig and Johnny Depp. There is even a website called "celebrity-sunglasses-finder.com" that has a huge index of celebrities and the sunglasses they wear on screen and off.
The structure of all sunglasses are more are less the same. The main body of the glasses is known as the frame, which holds the lenses and has two arms attached that rest on the wear's head. Most common frame materials are metal, plastic and cellulose acetate. Lenses are usually made from plastic or acrylic. Sunglasses have different tints on the lenses to block sunlight. Blue-blocking lenses are tinted amber to block blue light which is found to age eyes faster. Polarized lenses are lenses that eliminate glare from powerful light sources. Lastly, gradient lenses are lenses tinted on the top but slowly fades towards the bottom.
Most people are familiar with the brand Ray-ban for their Wayfarer and Aviator sunglasses. Ray-ban owe a lot of their modern popularity to actor Tom Cruise for his use of the Aviator in 1986's Top Gun and his use of the Wayfarer in his breakout 1983's Risky Business. The original Wayfarer costs around $150 and the Aviator starts at $200. Sunglasses can get expensive but the quality also increases. Persol are more expensive than Ray-bans but they offer different features such as foldable sunglasses. Oliver Peoples is the name brand of expensive eyewear, immortalized in such films such as American Psycho with Christian Bale. Their O'Malley frame is still their most popular, ranging from $350 - $450 not including prescription lenses which can cost up to $200.
One major problem with sunglasses and college students is that sunglasses can be fragile and can be easily crushed by a physic's textbook. The most durable material for sunglasses is cellulose acetate. My favorite brand who uses this material is Selima Optique. Each frame is hand made in France and the finished product is extremely durable. If you walk into any Selima store, the representative will gladly demonstrate this by bending the frame. Selima frames have been made poplar by Ryan Gosling's use of the Chad frame in Crazy Stupid Love and the Money 2 frame in Drive. I was lucky enough to meet and talk to Selima and the company genuinely cares about their products and will do anything to help you find your new look.
In conclusion, one of the most important accessories to any wardrobe are sunglasses. Whether they be sleek and metal or oversized and plastic, there's no more fashionable way to protect your eyes from the sun than putting on a pair of designer shades.