Eyeglasses, as well as sunglasses, are composed of four major parts: temples, frame, hinges and lenses. These parts are made from a variety of materials, each dictating weight, fit and quality. No matter the manufacturer, the same materials continue to be used time and time again. Special materials such as wood, precious metals and bone can be used, but are not the norm.
Temple Materials
The temples–also referred to as “legs,” “stems” and “ear pieces”–are what keep the eyeglasses on your head. Materials such as zyl (medium-grade plastic), optyl (high-grade plastic-nylon), titanium (strong, lightweight metal) and steel alloy (a heavier combination of metals) are most frequently used in manufacturing. While the plastic tends to be the most sturdy, the titanium is typically easier to adjust and weighs much less.
Hinge Materials
The hinges connect the temples to the frames and work to close the temples when the eyeglasses are not in use. Usually, despite the overall material used in manufacturing the eyeglasses (titanium, plastic, etc.), the hinges are made from high-quality steel alloy. They are composed of two pieces, secured by a common eyeglass screw, which is also made of steel alloy.
Frame Materials
The frame, which holds the lenses and sits on the face, can come in a variety of materials. Depending on cost, the frame can be made from lesser materials, such as plastic and steel alloy, up to the more pricey materials like gold, platinum and ivory. Wood frames, as well as temples, are sometimes available, but they tend to cost much more and are harder to find. In addition, the nose-piece frames of the eyeglasses are typically made from whichever material is being used, and the adjoining nose pieces are made from plastic and/or rubber.
Lens Materials
The lenses on eyeglasses and sunglasses are made from one of three common materials: CR-39 (durable plastic), polycarbonate plastic (shatter-resistant plastic) or glass. Whereas the glass is very hard to scratch and is prone to cracking and breaking, the polycarbonate almost never breaks, but it can scratch very easily. CR-39 is typically the default material for prescription lenses unless the consumer’s prescription is too high, in which the material is switched to polycarbonate that can be made much thinner to fit in the frames.
Combinations
Combinations of materials are also common on frames for eyeglasses. Typically, wood temples are placed on frames with precious materials such as platinum and gold and are available on higher-priced items. Carved wood and ivory temples are standard on the more exclusive brands. Precious stones like diamonds and emeralds, as well as crystals, can also adorn eyeglass frames.