High-End Apple Watches Use Sapphire Crystal Glass, original image from gearopen.com
As the window to your timepiece, the watch crystal takes some of the hardest hits, and the brunt of the everyday wear and tear. To extend the life of your watch crystal, crystals are made of different materials to ensure different kinds of strength. Plastic crystals are the most flexible of all the watch crystals, and therefore are used in a wide range of watches. Glass crystals are also common in watches.