Everything You Need to Know About Jewel Bearings


A common bearing is a mechanical component that minimizes friction between two parts. This seems to be very simple, but the bearing has become an increasingly important aspect of many projects, as they actually help thing run smoothly. Electric drills, axles, precision equipment and other applications utilize bearings to reduce friction, but recently more versatile bearings are in demand.

The invention of jewel bearing, consisting of some hard grinders, such as diamond or sapphire, can survive in the most difficult environment, while they are both accurate and reliable. This article will explore jewel bearings, how to operate, and what are the advantages of them over more popular choices.

What is a Jewel Bearing?

Any bearing goal is to reduce the friction between the two surfaces, relative to each other in contact and motion. In short, jewel bearings are simply made of precious jewels, such as ruby, sapphire and other types of corundum (alumina form). These materials are one of the hardest substances on earth, which accounts for extremely resistant bearings.

They have a low friction coefficient, and even in an extremely environment, it is not easy to wear. These are most commonly used in watches that require precise timing and durability, but have been found to be useful in other applications where lubrication is not available or conventional bearings fail. Jewel bearings can be made from real gems or synthetic gems, but synthetic corundum is more uniform, which makes the bearings more stable and uniform.

Applications of Jewel Bearings

Jewel bearings are best suited for low load, low temperature environments, where its excellent friction reduction maximizes. These bearings are famous in the manufacture of mechanical watches because they are small, highly accurate tools, and very suitable for consistent timing.

Although specialized, jewel bearing now finds more purposes in medical equipment and scientific instruments. They have recently been used for sensitive instruments that require high measurement resolution, such as dial caliper, universal joint, gyroscope, dial indicator, compass, current gauge, or even flow meter for process engineering applications. Jewel bearings have excellent consistency and flexibility, so these bearings might just be suitable for your project.

Advantages and Disadvantages of Jewel Bearings

  • Jewel bearings have traditionally been preserved for use in watches, but they have recently found their use as an attractive alternative to other traditional bearings. The following is a list of the main advantages of jewel bearings:
  • Jewel bearings can be incredibly small (minimum shaft size  0.006 “), and the friction coefficient of jewel bearings is very impressive (0.10-0.15) when steel is used on sapphire.
  • Jewel bearings are not much affected by acids, alkalis, and high temperature environments (2050 degree C or 3700 degree F and above).
  • Jewel bearings can be used with or without lubricants and performs best in low speed axial oscillation applications.
  • These bearings are lightweight but durable and resistant to aging.

With all these great advantages, Jewel bearings have some obvious drawbacks:

  • Jewel bearings are strong, but very fragile and must be combined with protective covers/equipment to maintain normal functionality.
  • Jewel bearings are often smaller in size. Medium to large jewel bearings are difficult to manufacture and increase the risk of breakage.
  • If the jewel bearing is not axially loaded, the change in friction will be large and the room for failure will be large.
  • Although cheaper to manufacture than some ball bearings, jewel bearings require special processing equipment, which is expensive and difficult to operate. Moreover, their small size leaves little room for margin of error.