There are basically 3 types of crowns for wristwatches: plain, dustproof and water resistant. They come in a variety of diameters and thickness. The crown screws onto the stem which is the thin shaft that inserts into the watch movement. Watch cases requiring a water-resistant crown will have a pipe coming out of the case through which the stem fits through.
Jewels are used extensively in vintage and modern watches due to their low friction and low wear characteristics. Low friction is vitally important, especially at the Balance Pivots, to reduce interference to the free motion of the oscillating balance wheel.
Steel components in a watch can become magnetized when exposed to a magnetic field, and the most likely source is an owner who unknowingly gets near a permanent magnet or high power electrical cable during normal day to day life.
How the basic club tooth lever escapement works. The picture below shows the basic layout of the club tooth lever escapement. In this picture you are looking down from the top. For the sake of this article, I am leaving out the safety parts of the balance which...