Construction of Sunglass --
Lens - The color of the lens can vary by style, fashion, and purpose, but for general use, green, grey, yellow, or brown is recommended to avoid or minimize color distortion which would be dangerous when, for instance, driving a car. Gray lenses are considered neutral because they do not enhance contrast or distort colors. Blue blocking sunglasses typically also block some light of other colors to function well in full sunlight. Some low blue glasses are for use inside at night to avoid suppression of the sleep promoting hormone melatonin. A mirrored coating can also be applied to the lens. This mirrored coating reflects some of the light when it hits the lens before it is transmitted through the lens making it useful in bright conditions. The color of the mirrored surface is irrelevant to the color of the lens. For example, a gray lens can have a blue mirror coating, and a brown lens can have a silver coating. Polycarbonate plastic lenses are the lightest, and are also almost shatterproof, making them good for impact protection. CR-39 is the most common plastic lens, due to their low weight, high scratch resistance, and low transparency for ultraviolet and infrared radiation.
Frames -Frames are generally made from plastic, nylon, a metal or metal alloy. Nylon frames are usually used in sports because they are light weight and flexible. They are able to bend slightly and return to their original shape instead of breaking when pressure is applied to them. This flex can also help the glasses grip better on the wearer's face. Metal frames are usually more rigid than nylon frames thus they can be more easily damaged when participating in sporty activities, but this is not to say that they cannot be used for such activities. Frames can be made to hold the lenses in several different ways. There are three common styles: full frame, half frame, and frameless. Full frame glasses have the frame go all around the lenses. Half frames go around only half the lens, typically the frames attach to the top of the lenses and on the side near the top. Frameless glasses have no frame around the lenses and the ear stems are attached directly to the lenses. There are two styles of frameless glasses: those that have a piece of frame material connecting the two lenses together, and those that are a single lens with ear stems on each side.
Nose Bridge- Nose bridges allow support between the lens and the face. Nose bridges also prevent pressure marks caused by the weight of the lens or frame on the cheeks. People with large noses may need a low nose bridge on their sunglasses. People with medium noses may need a low or medium nose bridge.

Oversize sunglasses are often used for humorous purposes, and look like a pair of sunglasses that is extremely large for the face. They usually come in bright colors with colored lenses and can be purchased cheaply. Over recent years however, moderately oversized sunglasses have become a fashion trend. There are many variations, such as the 'Onassis', discussed below, and Dior white sunglasses. Onassis glasses are very large sunglasses worn by women. This style of sunglasses is said to mimic the kind most famously worn by Jacqueline Kennedy Onassis in the 1960s.