The second group is softer. Cat eye, oval and round frames lift at the outer corner or curve all the way around, and they do something a square cannot: they make a plain outfit look planned. I wear them with a slip dress, a knit and a pencil skirt, or just a gray sweatshirt when I want to look a bit more finished.

The Medusa Biggie Oval Sunglasses, 51mm, are the pair with the most personality here, and the name tells you the Medusa is meant to be seen. The Cat Eye Sunglasses in 54mm and 55mm are the ones I would try first if you are new to the shape, because they read as a gentle lift rather than a big wing. The VE4488U Cat Eye Sunglasses, 53mm, are a little smaller and sharper. The 56mm cat eyes are the widest in the group, and they ask for a bold lip or a really simple outfit, not both.

On the oval side, the VE4487 Oval Sunglasses, 54mm, are the neat pair, the 55mm is a touch rounder, and the many Oval Sunglasses in 56mm are the roomy ones. I like an oval with a trench and a loose braid, because the curve softens the stiffness of the coat.

Here is the trick for any of these: hold your head still and look straight into a mirror. The outer corner of a cat eye should point toward your temple, not your ear, and an oval should not cut across your cheekbone. If it does, go down a size, which is why these are written with the millimeters.

The last group is the one for people who say they just want sunglasses that go with everything. Aviators, shields and flat tops are the shapes you can throw on with a white tee, a leather jacket or a swimsuit cover-up, and they work on a long drive or a short walk to lunch. There are eight pairs here, so this is the smallest group, and it is also the quickest to choose from.

The Aviator Sunglasses in 58mm, 60mm and 61mm are the classic teardrop, and the VE2283 Aviator Sunglasses, 61mm, is the one with a model name, which makes it easy to find again. The 58mm is the smallest and most wearable day to day. The Brow Bar Aviator Sunglasses, 60mm, add a bar across the top, which gives you a slightly flat-topped look and a bit of attitude. The Vance aviator sunglasses in brown are the warm, softer pair, and I would wear them with cream knitwear and gold earrings.

The two Shield Sunglasses, one of them listed as 135mm, are the boldest pair in the edit. A shield covers the brow and the cheek in a single piece, so it feels more like a visor than a pair of glasses. I would wear them with something very quiet, like a gray tank and wide trousers, so the face does the talking.

What I would skip: a shield or a big aviator if you mostly want something to wear while you walk the dog or run errands with a hat on, because a wide frame and a brim fight each other. Skip anything you have not tried on with the outfit you plan to wear, too. A pair that looks great on a screen can feel very different once the temples meet your hair and your earrings.

Here is how I would pick. First, decide the outfit, not the face. A sharp blazer wants a square or rectangle, a soft dress wants a cat eye or an oval, and denim wants an aviator.

Then check the millimeters. The number in the name is the width of the lens, so use a pair you already own as your reference. Try the pair on in daylight, near a window, and move your head from side to side. If they slip when you look down, they are too large.

Last, the label. The American Academy of Ophthalmology says to look for sunglasses that block 99 or 100 percent of all UV light, and that a label reading UV absorption up to 400nm means the same as 100 percent. It also says long-term UV exposure is linked to cataracts and eye growths. So check the tag or the product page before you buy, and do not assume a dark lens protects you.

The Greca, Versace's Greek key pattern, first appeared in a collection in Fall-Winter 1988 and has stayed a brand code ever since. If you spot it on a pair, that is the small detail I would look for. If you want to keep browsing, I also put together Quay Sunglasses and Tom Ford Glasses for Women.