Watches and Jewels
The pocket watch was first mentioned in a letter from a famous Italian clock maker in 1462 and by then end of the 15th century spring driven pocket watches were appearing all over Europe. Today watches of any quality will be jeweled, since up until the 1720ís all watches were based on the verge escapement which involved a high amount of friction and no jeweling as a result these watches were highly inaccurate.
Jewel bearing were invented by Nicolas Fatio de Duillier to prevent the wear of the insides of the watch and make them more accurate time pieces. Watch that do not have jeweling before this time that are still around today have been known to gain as much as an hour a day in time. Originally natural stones were used for this process mostly rubies and garnet but sometimes sapphire and diamonds. These stones were of low quality and unsuitable as gem stones. In 1902 a process to make synthetic sapphires and rubies was invented now virtually all watch jewels are synthetic.
The most common type of watch jewel is the hole jewel. Hole jewels are placed inside the watch to reduce both friction and ear to the moving parts. Normally they are shaped like flying saucers and placed in a carefully shaped and sized hole. The other type of jewels used in watch making are cap jewels, roller jewels and pallet jewels.
Cap jewels are just that they are a cap for the hole jewel. Perfectly sized to fit on top of the hole jewel offering better performance and lower friction. The roller jewel also known as the impulse jewel is a ruby or sapphire that is shaped into a thin rod. This thin rod is responsible for holding the balance wheel to the pallet fork. Finally the pallet jewels are rectangular jewels that fit on the pallet fork one on each side and are the part that actually engages with the escape wheel to control the rate of the movement.
Watches have different number of jewels but all watches should have at the very least 7 jewels. A watch that is considered fully jeweled will have 17 jewels. Watches that have jewels beyond 17 or often said to have no improvement in timekeeping or in the life of the watch most likely these jewels are added as a marketing gimmick. Since these jewels have no value at all. The watch with the most jewels ever produced is the Waltham 100 Jewel watch movement although it is said that 83 of these tiny jewels are non functional. Oddly enough there is one spot where a jewel is missing in the ring therefore adding to the argument that these jewel are unnecessary and only to inflate the jewel count, adding this jewel would have brought the number to 101 a number that wasnít so great with the marketing team at the time.