Sunglasses are like fragrances: It's fun to try new styles, but a classic, great-looking pair is key to developing a signature look. Somewhat surprisingly, this sartorial staple didn't become an option—let alone a mainstay—in men's wardrobes until 1919, when Sam Foster of the Foster Grant Company (one of the country's oldest sunglasses manufacturers) introduced the first modern pair in the Woolworth's on the Atlantic City boardwalk.

Before that, sunglasses were used for medical purposes. "Doctors used to prescribe tinted sunglasses to syphilis patients," says Warby Parker co-CEO Neil Blumenthal. "I guess they were hypersensitive to bright light."

But the evolution of stylish sunglasses really started with Ray-Bans. The still-iconic brand was created by Bausch & Lomb in 1937 for U.S. Army pilots. According to Alex van Klaveren and Zoe Nightingale Wiseman of Monocle Order, an online membership devoted solely to sunglasses, Ray-Bans were also designed to look sharp with pilots' uniforms, and when a flurry of flashbulbs captured General Douglas MacArthur (right) wearing a pair as he landed in the Philippines, the Aviators officially cemented their place in modern American style (his corn-cob pipe, however, never caught on).

The brand continued to branch out beyond the military with plastic frames named after those who prefer traveling on solid ground. Of course, it didn't hurt sales when Wayfarers were soon spotted on icons like James Dean and Bob Dylan (below, left and right).

What will the sunglasses of the future look like? Monocle Order's Wiseman is particularly impressed by the application of 3-D printing by companies like Mykita and Black Eyewear, which also uses carbon fiber and a titanium core for durability.

"Using a variant of nylon called Polamide, companies have been constructing eyewear by making a CAD [computer-aided design] drawing and using programs that create their designs instantly," Wiseman says. "The material, which feels like a mixture of leather and wood, is four times lighter than a standard acetate frame and still half as light as titanium. The other upside is it's insanely flexible and strong."

While trends are always changing, both Wiseman and Blumenthal are seeing more men buy shades in bold colors. But whether or not you want try a brighter hue, finding the best pair is all about fit. Here, Wiseman and Blumenthal offer tips on how to find the right frames shape for your face.

Round Face
Try a geometric or rectangular pair, like Perseus, by Ksubi.

Square Face
Blumenthal says guys with a square jawline should go for frames with "soft, round angles to balance everything out." Try Hercule Poirot, by Andy Wolf.

Long Face
According to Wiseman, people with longer faces should pick sunglasses that add width—think larger frames with strong, horizontal lines like the 6002 Sunglasses by Carerra.

Oval Face
"If you have an oval face, you're in luck," Blumenthal says. "You can wear whatever you want since your ratios are already even. Just think in terms of opposites. The more angular your features, the rounder your glasses should be, and vice versa." She recommends Super's Flat Top Francis.

Heart-Shaped Face
Heart-shaped faces can get away with oversize frames or "any frame that's wider at the bottom, to minimize the juxtaposition between the width at the top of the face and a narrow chin," Blumenthal says. Try Warby Parker's Beckett.

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