Exact technical stones widely apply to the clocks, instrument gages of oil products, gas, vapor, water and as the heat meter in recording barometers, hydrometers and in many other special instruments, and also the devices, working on a basis of jet technologies (needleless injectors for local anesthesia).
For example, the jewel holes with a cylindrical aperture such as HC are applied as angular-contract bearings with rather slowly rotating axes of a clockwork. For reduction of a contact surface between a pin and a surface of the stone aperture, forming cylindrical jewel holes, such as НN, carry out as some arc. It reduces considerably the friction in support, and also improves the conditions of greasing.
Jewel holes of spherical type HS are applied in the clockworks as the radial bearings to the pins of the most responsible unit of the clocks - balance.
Cap jewels are applied as basic bearings in the combination with the jewel spherical holes such as HS.
Axial bearing plays a role of the support in the electric, optical, astronomical and other instruments. The rotating part of the majority electric instruments is mounted on the supports, which are consisted of the conic form pins, having the internal cone, which is terminated by the spherical surface with the greater radius, than a surface of a pin, it provides the main requirement for the moment of friction in the support, which would remain small during the long time of the instrument exploitation.
Corund nozzles are applied for the needleless injectors, and also for the metal arc cutting extra-high pressure (water or some medical preparation moves under extra-high pressure and it is thrown out through the corund nozzle, forming thus a dense high-speed jet).