Wristwatch
A wristwatch is a time piece designed to be worn around the wrist, held together by a band. Modern wristwatches are often referred to as watches, and are mostly digital or electronic, despite having either an analog or digital appearance. There are wristwatches that are still entirely mechanical but because of the higher manufacturing and maintenance cost, these are becoming more rare and are considered "luxury items" or "antiques".
Anatomy
A wristwatch is comprised of three main pieces: a watchband, the watchface, and the crystal which protects in components inside the watchface. Most crystals are made from plexiglass, ordinary glass referred to as "mineral glass", or synthetic sapphire. Some crystals are made from a combination of sapphire and mineral glass, usually assembled in layers. Seiko, a large watchmaker, makes a type of crystal that is mineral glass covered by a layer of synthetic sapphire which it called "Sapphlex".
The three types of crystals have different costs, plexiglass being the cheapest, is the least likely to shatter but is extremely scratch-prone. Mineral glass is tempered is more likely to break but is more scratch-resistant. Synthetic sapphire, having the greatest hardness is the most expensive but is brittle, and easily shatters due to it's crystalline structure.