One thing that many watch buyers take for granted is the type of crystal that is protecting their watch. The main purpose of a watch crystal is to shield the dial from external forces like water and dust. While there are many different kinds of cuts (domed, faceted), the main types of crystal 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 not very scratch resistant. However, it's possible to polish the surface of an acrylic crystal to make it appear brand new. Plus: unlike other kinds, acrylic crystals are shatter resistant.
Mineral crystals are made of normal glass that has been heated and/or chemically hardened to be tougher and more scratch resistant. It's 7 times harder than acrylic crystal. Compared to acrylic, mineral crystals aren't shatter proof but is easily replaced. Many of the watches in Orient’s collection employ mineral crystals (like the Pilot's Watch and EM65).
Sapphire (or synthetic sapphire) crystals are the most scratch resistant of the three, and is 3 times harder than mineral crystal. This kind of crystal helps the watch to keep looking fresh and brand new. The Orient Star, M-Force, and the newly released EM65 USA collections are among several Orient Watches that feature sapphire crystals. Our sapphire crystals are typically coated with an anti-reflective coating (some including Orient’s own Super Anti-Reflective Coating) that reduces glare and improves legibility of the dial.