Watch Jewels
Jewel bearings were invented and introduced in watches by Nicolas Fatio (or Facio) de Duillier and Pierre and Jacob Debaufre around 1702 to reduce friction. They did not become widely used until the mid 19th century. Until the 20th century they were ground from tiny pieces of natural gems. Watches often had garnet, quartz, or even glass jewels; only top quality watches used sapphire, ruby, or diamond. In 1902, a process to grow artificial sapphire crystals was invented, making jewels much cheaper. Jewels in modern watches are all synthetic sapphire or (usually) ruby, made of corundum (Al2O3), one of the hardest substances known. The only difference between sapphire and ruby is that different impurities have been added to change the color; there is no difference in their properties as a bearing. The advantage of using jewels is that their ultrahard slick surface has a lower coefficient of friction with metal. The static coefficient of friction of steel-on-steel is 0.58, while that of sapphire-on-steel is 0.10-0.15.
Read more about this topic: Mechanical Watch
Famous quotes containing the words watch and/or jewels:
“In night when colours all to black are cast,
Distinction lost, or gone down with the light;
The eye—a watch to inward senses placed,
Not seeing, yet still having power of sight—
Gives vain alarums to the inward sense”
—Fulke Greville (1554–1628)
“The lakes are something which you are unprepared for; they lie up so high, exposed to the light, and the forest is diminished to a fine fringe on their edges, with here and there a blue mountain, like amethyst jewels set around some jewel of the first water,—so anterior, so superior, to all the changes that are to take place on their shores, even now civil and refined, and fair as they can ever be.”
—Henry David Thoreau (1817–1862)