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  • Eyewear Lexicon

    Eyewear Lexicon

Eyewear Lexicon




A material widely used in plastic frames. Due to its high transparency, acetate provides bright and beautiful lustrous colors.


A light and soft metal with high processability in production.  While 40% lighter than titanium, it is inferior in terms of strength and corrosion resistance.  Used for many years in the manufacturing of temples.


A frame shape used by the US air force that has become an eyewear icon.

A measurement

The width / horizontal measurement of a lens.

AR Coating

Anti-Reflective coating.  A coating that eliminates the reflection from the concave side of the lens, and protects it from scratches and/or adherence of dirt.

Beta Titanium

A titanium alloy consisting of titanium, vanadium and aluminum. Stronger than pure titanium, but just as lightweight and corrosion-resistant. Due to its elastic properties, even a thinly designed beta titanium frame retains its strength.


The part between the two rims, which extends across the nose.

B measurement

The depth / vertical measurement of the lens.

Bifocal Lens

A lens with two focal areas: typically with a farsighted correction on top and nearsighted area on the bottom of the lens.

Carbon Fiber

It is used in the body of racing cars, car fenders, electric machine devices, and, to a degree, in eyewear. It is extremely abrasion-, heat-, and acid-resistant.


A manufacturing process mainly used to create end pieces or ornamental parts. A processing method in which beryllium copper or titanium is melted then cooled in a mold to form the parts.


A technique used to decorate certain details of the frame with resin. Its stereoscopic and transparent effect creates a decorative and high-value frame.


A square shape transformed from the aviator.

Cat Eye

A retro frame style in which the outer edges of the almond shaped lenses are upswept. Also called the 'Monroe style' as the style was recognizably worn by Marilyn Monroe in a film.

CR lens

A commonly used lens made of a resin called CR 39 with a wide variety of colors ranging from full colors to gradated colors.


A very light aluminum alloy, inferior to titanium in strength and corrosion-resistance, but lighter in weight.


DBL = Distance Between the Lenses

Also called the bridge size, it refers to the minimum horizontal distance between the lenses.


A new titanium alloy that offers high flexibility and memory function, and is nickel free.  Patented by CHARMANT Group.

Electric Coating

A coating technique that electrically applies colored resin onto the surface of a frame. It embellishes the frame while also making it corrosion-resistant.


A secondary surface treatment of thin, highly adhesive colored film. Mostly used for the rim color to enhance embellishment. It provides a lighter expression than cloisonné.

 End Tip

The end of the temple that rests over the ear.


End Piece

The portion of the frame that extends outwards from the front piece and connects to the hinges.

ED measurement

ED = Effective Diameter.

It indicates the minimum size/diameter of the lens to be used.

Full Rim

The most traditional style of optical frames. This style most securely hold the lenses as they are entirely encased within the frame.


A dense, soft, and malleable metal bright yellow in color.  It does not tarnish when exposed to air or water.

18ct (composed of 75% gold) or 14ct (composed of 58% gold) are generally used in eyewear, while 24ct (pure gold) is too soft and therefore not suitable for eyewear.

German Silver

Otherwise known as nickel silver; it is an alloy containing copper, zinc, and nickel. Traditionally used in eyewear production.

Gold Plating

An electrical process of surface treatment used to cover a material with ionized metal (gold). It embellishes the frame and makes it corrosion-resistant.

Heat Transfer

A process used to decorate the frame by transferring the patterns from a decorated paper onto the frame.


The part of the frame that connects the frame front with the temple piece. Its function is to open and close the temple.

Half Rim

A frame style that uses a nylon cord to hold the lens; the rims are almost invisible.

Hard Coating

A coating to prevent a lens from getting scratched. 

Hydrophobic Coating

A lens coating that repels oil and water.

Ion Plating

A color coating technique used exclusively for titanium frames wherein a hard metallic compound is adhered to the frame through a chemical reaction between gas and ions in a plasma space. It embellishes the frame and reinforces the corrosion-resistant properties of the frame. This plating method is very eco-friendly, as it uses little water.

Mono Block Hinge

A hinge piece with an integrated rim lock piece.

Mineral Lens

A lens made of glass. While heavier than plastic lenses, it is more scratch-resistant.

Mirror Coating

A lens coating which makes the lens reflective like a mirror.  By reducing the amount of sunlight that passes through the lens, glare is limited; as such this coating is often used for sport sunglasses.

Nickel Titanium (Nt)

A highly elastic memory titanium alloy. It is comprised of 50% nickel and 50% titanium.

Nose Pad

Used as a pair, they rest on either side of the nose and help to support glasses.

Nose-Pad Arm

The arm piece connecting the front piece and the nose pad.  It can be adjusted to position the frame.

Pure Titanium

A titanium material that is made of 99% genuine titanium. Excluding the screws and washers, CHARMANT's Pure Titanium frames are completely made of titanium. It is lightweight, corrosion-resistant, and hypoallergenic.

Precision Laser Welding

A welding technique which utilizes laser energy. Far more precise than conventional welding, it joins parts without damaging the material.  It provides a much stronger weld; and allows for the most delicate of pieces to be connected.  LineArt CHARMANT utilizes precision laser welding.


A latter production process in which frames are smoothed with wood chips and walnut shells in a tumbling barrel for several hours.




A traditional and classic lens shape, reminiscent of a rounded upside down triangle. Traditional and classic.


The distance between the center of a person’s pupils.  

This pupillary distance measurement is used when creating lenses to ensure the optical center of each lens is lined up to the wearer’s pupils for optimal visual clarity.

PC lens

A lens made of Polycarbonate. Polycarbonate lenses are thinner and lighter weight than traditional plastic lenses.  Its durability and scratch-resistance make these lenses ideal for sport style sunglasses and rimless styles.

Polarized Lens

A lens that eliminates horizontal glare, or reflected light, from surfaces such as water, sand, roads, and snow.  Great for driving and water-related activities.

Photochromic Lens

A lens that adjusts its darkness level based on the degree of light exposure.  The brighter the light, the darker the lens will be. 

Progressive Lens

A multifocal lens with gradual corrective powers changing from far- to nearsighted corrections. It offers a clean appearance without the borders of the different focal areas and the most natural visual correction of all multiple corrective lenses.


The part of the frame responsible for holding the lens. It also determines the shape of the lens.

Rim Lock

The small lock part on a rim wire used to open or close the rim when mounting the lens.


A frame style without a rim wire. The lenses are drilled and mounted directly onto the chassis. The style maintains the most natural facial impression as there is no border around the lenses. 


A shape close to the perfect circle. E.g. John Lennon's glasses.



Stainless Steel

A type of steel used in frame manufacturing.  It is corrosion-resistant, durable and lightweight.


A welding process employed to join separate metal parts. Metal pieces are joined with heat which acts to fuse the individual pieces.

Spray Color

A process of coloring in which powdered paint is sprayed and the colored surface is calcified. Spray color provides a variety of color expressions and embellishes the frame.

Spring Hinge

A hinge with a spring mechanism for comfortable wear. The hinge prevents the frame from deforming when putting it on or taking it off by releasing the tension.


A lightweight and corrosion-resistant metal. Titanium requires a high level of processing and surface treatment in eyewear production.

Its weight is half of nickel silver.


Commonly referred to as the “arm” of the frame, the temples extend from the frame front to the end tip, resting over the ears and holding the frame in place.

Z Titanium

A titanium alloy consisting of titanium, zirconium-titanium and niobium. The material is also used in the medical field as it is light, elastic, gentle, and safe for the human body. The frame provides a softer and gentler wearing comfort than that of Pure or Beta titanium.