Glass refers to the transparent cover on a watch face that allows you to view the watch dial and hands. Glass is available in different materials and qualities; however, at present, mineral glass are used by most manufacturers and, thus, seen on most watches on this website. Below, you are able to learn more about the different types of glass and their features.
To equip watches with mineral glass is very common as mineral glass are made from glass that has been heat treated or exposed to chemicals to make it more resistant to scratches. As a result, mineral glass is more robust compared to regular glass; however, scratches and dents may appear in time – sapphire is more resistant. If a glass is covered with scratches, it is recommended to have it replaced. Not just for aesthetic reasons, but mainly as material strength is reduced, making the glass more susceptible to shattering if subjected to bumps and bruises. A mineral glass has a Vickers hardness of 500-800.
Sapphire is the most expensive type of glass as sapphire glass is very resistant and made from crystallized aluminium oxide at high temperatures. Sapphire is more resistant than any other type of glass and rarely shatters as sapphire glass is extra resistant to scratches and known to be up to seven times harder than steel. Sapphire glasses have a Vickers hardness of 2200-2300 (significantly more than mineral crystals). Sapphire glasses are more expensive to produce and only quality watches come with sapphire glass. Thus, most Tissot and Certina watches are equipped with sapphire crystals.
Hesalite - or acrylic glass as it is also known - is the most inexpensive type of glass and used on a limited amount of watches. At this website, we offer approximately 10 different pocket watches fitted with hesalite crystal. On the upside, hesalite glass are very lightweight and do not break into tiny fragments if broken. However, on the downside, hesalite glass can be susceptible to scratches as they only have a Vickers hardness of approximately 500 – on a positive note, hesalite glass can be polished to remove minor scratches.