Sunglass frames are made from metal, plastic or beryllium. Metal frames, particularly expensive ones, are often made of mixtures of nickel and other metals such as silver. Plastic frames contain various materials, such as zyl,cellulose acetate propionate,nylon and castor oil. Beryllium, a steel-gray metal, is a lower-cost alternative to titanium eyewear.
In general, sunglass lenses are made of either plastic or glass. Plastic lenses are lightweight and come in different tints. plastic sunglass lenses can block 80% of UV rays and thus provide good protection from sunlight. While offering excellent optical quality, glass lenses are more susceptible to scratches. However, sunglasses frames are made of plastic and metal.