Why do Watches have Jewels?

            You must have heard people inquire about the number of jewels in a watch, while purchasing a mechanical wristwatch. The number of jewels is inscribed or printed on the outer cases or the dial of the watches. The reason is that the more the jewels used the better and more durable is the watch. Let us now see what are these jewels and why are they fitted into watches.

            A good watch is one that gives the accurate tie and does not easily go out of order. If you open a watch, you will notice that the internal mechanism of a watch is very complicated. It has many parts of different sizes. A watch roughly contains 211 parts. Amongst these parts is a small wheel that is always in motion.

Internal structure of watch

            Along with the wheel, there is a very fine spring called the mainspring. It is released through what is appropriately called a clockwork mechanism. When we wind the spring, energy gets stored in the spring, is finally released through a fine spring with a hair like wire, called a hair spring, which runs the balance wheel which is the timing mechanism of the watch. The energy stored in the mainspring runs the watch and keeps it ticking. There are many other wheels which are constantly revolving. These wheels move the hour, minute and second hands. The axles of these wheels rest on pivots. When the wheels rotate, friction is generated between the axles ad the pivots.

            Due to this friction, pivots and axles can wear out soon. With the result that the watch starts slowing down or runs erratically, and finally stop working. To reduce this friction, small pieces of very hard but smooth material is used as pivots. These small pieces are called jewels. The material usually used as jewels includes semi-precious stones like agate, or even costly ones like ruby and sapphire. They are hardest jewels after to diamonds. The jewels re used to reduce friction between the axles and the pivots. Because of their harness, the jewels do not wear out soon and the watch does not go out of order easily.

            Hence, jewels are sued in watches to prolong their life. Nowadays, most watches use digital mechanisms. The heart of these watches is a quartz crystal which has a specific rate of vibration when subjected to an electric current the major advantage of the digital watch is high accuracy. Such watches have no mainspring, and run on button cells.