Mineral crystal glass is made from silica and is manufactured using regular tempered glass. This tempering process makes the mineral crystal much more scratch-resistant and able to handle great depths and pressure.
Since mineral crystal has more flexibility than sapphire crystal, we like to use this crystal in timepieces that are worn often like our models that are used for everyday wear.
Mineral crystal is less prone to shattering under pressure. Therefore, we have concluded that mineral crystal is more ideal in some models like our Promaster Dive models. As dive models are used under water pressure, mineral crystal is quite durable and flexible for this use. Mineral crystal will withstand the pressure of water when used for diving.
Sapphire is made from synthetic sapphire combined of crystallized aluminum oxide. Sapphire crystal is one of the hardest substances on earth. It ranks 9 on the Mohs scale, which is a system for rating the relative hardness of various materials where a diamond measures 10, the highest rating. Sapphire crystals are “scratch resistant” or “virtually scratchproof” because they are very difficult to scratch. Only a diamond can scratch them.
Due to it’s durability, we use sapphire crystal for models such as our Atomic timekeeping models, Satellite GPS models, and Diamond models to protect the additional assets on these styles.
As with any item we wear, each wearing brings a different set of circumstances that may result in an action not seen prior. Sometimes crystals will become scratched will become damaged without our knowledge or awareness of when such damage may have happened.