Sapphire lenses are made of synthetic sapphire, which is a hard and transparent material made of high-temperature crystallized alumina. While it has high hardness, it is also more brittle than mineral glass or organic glass.

From a chemical perspective, synthetic sapphire can be used for jewelry like natural sapphire, but does not require coloring agents to give the gemstone color. When heated, artificial crystals take on a spherical shape and are then sawed into pieces using a diamond saw. These discs are then ground and polished into lenses (one of the reasons why sapphire crystals are relatively expensive is that the tools required to manufacture them are expensive). Both natural and artificial materials have high hardness, with a Mohs hardness of 9 (Mohs hardness is a system for evaluating the relative hardness of different materials, with diamonds having a Mohs hardness of 10).

Sapphire lenses are often advertised as' scratch resistant ', which means they are difficult to scratch, but not necessarily impossible to scratch. Diamonds can scratch them, while materials with a Mohs hardness of 9-10 and added with silicon carbide are harder than sapphire and, like diamonds, can also scratch them. These materials are used on furniture or walls. If users of sapphire lenses do not pay attention to rubbing the surface of this material, it may cause scratches.

Some mineral glass crystals are also promoted as scratch resistant, with a hard coating on their surface that helps them resist scratching. One or both sides of the "anti reflective" crystal are coated with a substance (the same substance used on reflective glass) to reduce reflection and make the surface more readable. Anti reflective crystals can be made from mineral crystals or synthetic sapphire lenses. An interesting feature of these crystals is that they are almost invisible when viewed from the front because they do not reflect any light. In some cases, coatings can turn crystals blue, just like glass.