People with square face have wide cheeks, short face, they look very strong. In order to soft facial lines, they can choose a slight curve frame, which can let face look softer, and ease the too wider cheek. In addition, they should choose the frame slightly wider than the face, which can make the face look slightly long.
Choosing a sunglasses frame that contrast with your face shape is the general principle. People with square face may well be flattered by oval and round frames or glasses with temples that are center set or that connect at the top of the frame.
Besides butterfly shaped glasses are also a nice choice. Do remember to avoid geometric and square shaped frames that accentuate angles of the face. Since vintage style is hot recently, you may choose aviator sunglasses which are quite classic. And wrap around sunglasses are also very popular that they can make people fairly attractive and can offer the more comprehensive protection from UV lights, dust, wind and so on.
People with square faces while selecting sunglasses should notice the curve of the frame. So, round or oval are help to remit the mistakes of square shape faces. Red colored sunglasses make your friend look powerful and confident. Purple will make her a grace and elegant lady. Blue is the color makes people look cool. So, what is feeling you want to take to your friend? By the way, if she always drives with sunglasses, you should avoid red, green and yellow, or it can be a hidden danger of a traffic accident.