What’s protecting your watch? While we’ve talked about how you can keep your watch in tip-top shape, we haven’t discussed the first line of defense, which are the crystal and the case. Watches see the most action when on the wrist, but it’s also the time when the crystal is the most exposed and vulnerable. We’re back once again to talk all things crystals.

The main purpose of a watch crystal is to shield the dial and movement from external forces, like water and dust. Although there are many different kinds of cuts (flat, domed, faceted), the most common types are acrylic, mineral, and sapphire.

Acrylic crystals are essentially the same material as plastic and plexiglass and were commonly used on watches until the late 1970’s. Acrylic crystals are cost effective and quite prone to being scratched. The tradeoff here is cost and the ability to re-polish the surface to remove the scratches. Additionally, acrylic crystals are more shatter resistant than mineral and sapphire.

Mineral crystals are made of normal glass that have been heated and/or chemically hardened to be tougher. Technically, they are 7 times harder than acrylic crystal and more scratch resistant. But with a higher hardness rating it has a higher chance of shattering. Like acrylic crystals though, they are lower cost and easily replaceable. Many of the watches in Orient’s collection employ mineral crystals, such as the AA02.

Sapphire (or synthetic sapphire) crystals are the most scratch resistant of the bunch, and are 3 times harder than mineral crystal. They help keep watches like the Kamasu and RA-AK00 looking brand new and scratch-free. And while most people would prefer a sapphire crystal, there are a few tradeoffs to consider: they are likely to shatter on impact, and are a lot pricier to replace.