Professional publications of doctors 

Why do we need stones in mechanical watches? Time to collect stones

Very often on the case of a good mechanical watch you can find the marking “17 stones”, “21 stones” or even “100 stones”. What do these inscriptions mean? What kind of stones are we talking about? And most importantly, how does the number of stones affect the cost of the watch?

Watch stones - the main purpose

First of all, it should be noted that we are not talking about the decorative design of the watch case, but the stones involved directly in the watch mechanism. According to the official definition given in NIHS 94-10, adopted in 1965 by the Swiss organization NIHS (Normes de l’industrie Horloge Suisse), stones in a watch movement have the function of "stabilizing friction and reducing wear on the contacting surfaces of the movement." In addition, the stones can act as an accumulator for watch grease.

Mechanical watches, especially wristwatches, are incredibly complex objects from an engineering point of view. Inside the small case there are several hundred parts, the thickness of which can be measured in microns. Some of the watch parts vibrate more than 7,000 times an hour, around the clock, 7 days a week. Despite the fact that modern watch movements are made of the latest super-strong alloys and using the most advanced technologies, such a heavy load leads to rapid wear of the metal parts of the movement and, accordingly, to violations of the accuracy of the movement.

Precious stones are used as pivots for the axes of the main parts of the movement. The stones have a denser crystalline structure, they are easier to process and polish and do not corrode. In addition, some stones have a much higher wettability coefficient than metals, so they can also work as ideal keepers of watch grease.

History and modernity

For the first time, stones were used in watch movements at the beginning of the 18th century, when pocket watches became fashionable. In that era, natural rubies were used in the manufacture of watches. Modern technologies allow people to grow artificial stones, which in their qualities are absolutely not inferior to natural ones, but have a lower cost.

Today, artificial rubies and sapphires are mainly used in the manufacture of watch movements. The number of stones required for the simplest mechanism without complications is 17 (five stones for the pendulum, four for the anchor, two for the ratchet gear and six for driving the seconds hand). As the number of complications in watches increases, so does the number of stones. For example, in a self-winding watch there are already 23 of them, if there is a perpetual calendar - even more.

Less is Better

The Vacheron Constantin Reference 57260 watch, which is currently considered the most complex in the world, has 57 different complications and 242 jewels in the movement. But this is one of the extreme cases. In modern mechanical watches, it is customary to use 21 stones... There are also known curious situations when the number of stones in a watch is artificially increased to raise the prestige of a model.

The main thing to understand is that if the manufacturer indicates “100 jewels” on the watch case, and this is clearly not a Vacheron Constantin 57260 or Patek Philippe Caliber 89, then the only function of most stones in such watches is to increase the value.

Quartz watches do without stones at all, or have only 2 stones that serve as supports for the stepper motor rotor.

No matter how many stones and complications your watch has, its main function is to measure the time as accurately as possible. And if they cope with it, the rest becomes less important.

Watch pawnshop The collector will buy mechanical watches from famous Swiss brands for cash. We specialize in expensive Swiss watches, so we are able to quickly and fairly evaluate your watches. Working with us, you are guaranteed to receive:

  • quick decision making
  • payment of the entire amount in cash on the spot
  • complete confidentiality and security

Swiss watch movement- this is the holy of holies of mechanical clocks, where the uninitiated entry is strictly prohibited. Many myths are associated with the use of stones in the caliber of watches. For example, it was previously believed that the number of stones affects the quality of the move. Is this really so and why these stones are called precious - we will try to clarify in today's article. The main question on the surface is the role of stones in mechanisms. After all, not a single marking without indicating the number of stones inside the caliber.

Every watchmaker will answer without hesitation that the stones in watches are needed in order to stabilize friction and reduce the degree of wear of the contacting surfaces of the movement. The NIHS 94-10 standard on the function of stones in a movement was adopted in Switzerland in 1965.

Clock mechanism and mineral bearings

The watch mechanism is designed in such a way that its main axes are constantly under load: the mainspring forces them to rotate, and the spiral regulator restrains this rotation. The balance support has the greatest work: in addition to the reciprocating movements, a rather weighty balance is attached to it. The junction of the axle with the plate - the stationary part of the mechanism - is subjected to strong friction, and to stabilize it in Swiss watch device special bearings are used.

It is known that the coefficient of friction of hardened steel and ruby ​​is exactly the same as when paired with steel and brass. Why do watchmakers use precious minerals in Swiss watch movements? The pins of the axles, which are inserted into the bearing, are very small in diameter and are only one hundred microns. Therefore, the stones in watches are needed rather to increase the durability of the axle bearings in the movement, where reducing friction is a natural solution to the problem. The advantages of stone over metal are obvious: it does not oxidize or corrode, and a polished stone surface will retain its shape longer. The rocks cope better with the load from impacts from the fork arms and the pressure of the escape wheel lugs.

For the first time, the use of precious stones in a watch mechanism was proposed by George Graham, the founder of the Graham watch manufacture. In 1713, Graham invented the free escapement escapement, which is still used today. Graham's hand is responsible for the creation of more than three thousand copies of pocket watches, and each of them contains ruby ​​bearings. Starting in 1725, it was possible in the caliber.


Rubies in hours and their optimal amount

Rubies in hours are located inside the mechanism depending on the function. In the usual three-pointer, the optimal number of ruby ​​stones reaches seventeen. Sometimes the design approach forces you to change some of the stones for brass bearings, and in this case, the true number of stones is written in the characteristics of the watch. Each additional complication adds a number of stones to the movement.

There are many curious cases when the number of stones is several times greater than the required number. For example, markings that include fifty, eighty and even one hundred stones cause confusion among the buyer. A lot does not mean good. This move is misleading for beginners. All stones that are actually used in the movement of a Swiss watch are called functional. All other stones on the caliber perform a decorative function that does not fit into the standard marking accepted throughout the world.

Where are stones not needed? In a quartz watch. The only moment of load on the wheel train occurs when the stepper motor is turning. Due to the fact that there is no mechanical movement in quartz watches, wear is almost completely avoided. Therefore, if the number of one, two stones or without stones is indicated in the characteristics of a quartz watch, this does not mean anything terrible. Those manufactories that are of very high quality without a single stone.


Mechanical Swiss watches for two centuries they were made with real ruby ​​stones inside the mechanisms. The situation changed when the technology for growing artificial rubies was invented in 1902. Such a turn of history in many ways allowed the watch to be produced in large quantities. Nowadays, natural minerals are used very rarely, because artificial stones are more reliable in work and are easier to process than natural ones. Of course, the realization that the watch caliber contains natural rubies brings great aesthetic pleasure. But the use of synthetic stones does not diminish the value of real watch masterpieces.

Watch stones as a criterion for the quality of a watch movement

Regardless of the brand of mechanical watches, whether it is an expensive "Oris" or an ordinary "Flight", any wrist watch contains hour stones.

In turn, the number of stones in a watch movement is one of the main criteria for the quality of a watch. The significance of this factor is also confirmed by the fact that information about the presence of stones is usually displayed on the watch dial. Moreover, although we are talking about the stones inside the clock, and not in the external decorative inlay, the British call watch stones "jevels" - precious stones. So, what is the connection between the quality of a watch movement and the number of stones in it, what is their function and why are they considered precious?

Precious stones in watches are not used to decorate a piece, as, for example, they adorn Parker fountain pens and ballpoint pens. Any master watchmaker, without hesitation, will answer that the stones in watches are needed to reduce the coefficient of friction between the parts, which contributes to increasing the wear resistance of the entire watch movement. This is the formulation indicated in the NIHS 94-10 standards, which were adopted in Switzerland by the Normes de l "industrie Horloge Suisse organization in 1965. Although the first watches with rubies in the mechanism were made by the famous English watchmaker - George Gray (1673-1751) - at the beginning of the 18th century.He was the first to guess that by reducing the coefficient of friction, you can achieve high quality.By the way, it was he who in 1713 came up with the idea of ​​a free escapement mechanism, which is still used in watches. He has produced over 3,000 pocket watches, embodying the most advanced watchmaking ideas of the time, and in all his watches since 1725, axles, impulse rollers and pallets were made entirely of ruby.

However, it cannot be said that today watch stones are used solely to reduce friction in the movement. After all, the coefficient of friction between hardened steel and a watch stone is approximately equal to that of brass and steel. What is the expediency of using precious stones as bearings for watch movements?

The fact is that the diameter of the pins of the axes of pocket and wristwatches is very small (about 100 microns). It is known from the school physics course that the pressure force is directly dependent on the area of ​​the contacting surfaces. As a result, it can be concluded that watch stones are used not only to reduce friction, but also to preserve the axial supports. Plus, the stone is not subject to corrosion, and its polished surface retains its properties much longer than metal.

Today, artificial ruby ​​is an ideal material for making watch stones. This is justified by the fact that this material has high wear resistance, great hardness, it is perfectly processed, which is very important, it can be polished very qualitatively. Artificial ruby ​​also has an excellent wettability coefficient, which allows the watch oil to be retained on planes without loss, ensuring minimal wear of rubbing surfaces and smooth operation of the entire watch movement. In addition, artificial ruby ​​not only does not oxidize the lubricant over time, but does not even cause the slightest change in its properties.

Depending on the purpose of the watch stones, there are several types of them: overhead, pallets, impulsive and through.

The hemispherical surface of the overhead stones helps to reduce the friction in the bearings. As a rule, this type of stones is used as thrust bearings.

The shape of the "pallet" stone is a rectangular prism. This kind of watchstone is divided into entry pallets and exit pallets. Their purpose can be determined by the angle formed by the plane of the impulse and the plane of the base. The exit pallets have a sharper angle than the entrance pallets.

Impulse stones are used to transfer the interaction from the balance sheet to the truss fork. In section, they represent an incomplete ellipse, made in the form of a cylindrical pin.

Through stones are available with cylindrical and spherical holes. A stone with a cylindrical hole is used as a bearing for the pin of the tribe and the axles of the wheel system. Through stones with a spherical hole are used for the balance axle trunnions. The main feature of all through stones is the presence of an oiler - a special circular recess for keeping watch oil.

In electronic-mechanical watches, depending on the complexity of the mechanism and the availability of additional devices (calendars, a separate stopwatch, etc.), 17 or more stones are used. However, some manufacturers, knowing that the majority of consumers choose watches by the number of stones, use watch stones in the movement inappropriately (for example, place them around the self-winding rotor, etc.) just to write an impressive number on the dial. No matter how prestigious a manufacturer's brand is, be it Rado or Orient, the number of stones in a watch must correspond to the number of axles.

The stones in the movement are used to stabilize friction and increase the life of the contacting elements.

The source of energy in any watch movement is a spring, which outwardly resembles a flat steel band. When the clock is wound, it curls up and draws in energy. The other end of the spring band is attached to the drum, which transfers energy to the gears, which create a wheel system that provides energy transfer. The speed of rotation of the gears is controlled by the presence of a trigger, consisting of many moving elements mounted on the axles.

Any mechanism that includes rotating axles needs to minimize the friction of the moving elements on the base. The lower the friction, the longer the watch can run without winding and the longer the parts will last. Any other movement could use bearings, but watches use the same stones. They are not afraid of wear and corrosion, and the polished stone surface remains perfectly flat and clean for a long time. In addition, watch stones prolong the life of the movement, since the friction of the stone on the metal does not affect the state of the movement as much as the friction of two metal elements.

Special attention should be paid to the impulse stone, which is installed on the pendulum and constantly strikes the truss of the truss fork. The impulse stone must be particularly wear-resistant.

What stones are used in the watch movement?

Natural diamonds and rubies are used in their wristwatches only by manufacturers of premium products, and then usually only in limited editions or in models made to order. Mostly stones in watches are artificial sapphires and rubies. Some watch manufacturers, such as Seiko, even have separate divisions that specialize only in the preparation of watch stones. By the way, artificial stones cope with their tasks even better, as they have a more uniform structure and do not contain impurities.

Number of stones in hours

It is worth clarifying right away that if in some watches there are 17 stones, and in others 40, this does not mean that the latter are 2 times better than the first. In a self-winding watch with three hands, a maximum of 25 jewels can be set, it will no longer be possible to install it even with a great desire. Most of the stones are used only in watches with chronographs and other complex movements. However, some manufacturers, trying to attract the attention of the buyer, deliberately install stones in places where they are not needed.

Modern manufacturers of mechanical watches use stones for four purposes:

  • Through (accept radial loads in axial supports).
  • Overhead (reduce friction at the ends of the axles).
  • Impulsive (transfer energy to balance).
  • Pallets (ensure the normal operation of the anchor fork).

The basis of any wristwatch is through stones, of which there should be at least twelve. Each through-stone has a small indentation for watch oil. The generally accepted standard indicates that at least 17 jewels should be installed in watches, although in recent years there has been a clear trend towards using 21 jewels, which has a positive effect on the durability of movements.