Whats the difference between acrylic, mineral, and sapphire crystals?
An acrylic watch crystal (i.e. the see-through window above the dial) is a kind of plastic, which has the advantage of being resistant to shattering, but can be scratched easily. Fortunately, scratches can be easily removed from acrylic. Mineral crystal is a kind of glass, which is more scratch resistant than acrylic, but not as as good as sapphire. Mineral crystals are also somewhat better at shatter resistance compared with sapphire. Unlike acrylic, scratches in mineral glass are more difficult to buff out; and unlike sapphire, mineral glass will scratch. In my opinion, the mineral crystal seems to be a poor compromise between the two extremes. A sapphire crystal is indeed made of synthetic sapphire, which is a transparent form of corundum, or aluminum oxide (Al2O3). It is extremely hard (Moh’s scale 9), and will resist scratching by most substances short of diamonds. However, if struck sharply and from the correct direction, sapphire will shatter. Despite the relatively large size c
