The number of jewels in a movement was a true indicator of its quality. In most watches the jewels are used for all the pivot points in the gear train, as well as in the anti-shock settings. As watches became complicated, the number of jewels gradually increased in numbers.
The use of jewels was heavily marketed to make the watches seem to be of a higher quality than they actually were. So when you see watches with say, 85 jewels or so, you know you are being taken for a ride. Nicolas Fatio de Duillier, Peter Debaufre, and Jacob Debaufre introduced jewel bearings for use in watches way back in and also received an English patent for the idea. It made a lot of sense as many gemstones are much harder than metal, especially diamonds, but also sapphires and rubies corundum , which are identical in makeup except for their colour.
They are also slicker than metal, which means they manage to protect vulnerable areas while encouraging a smoother, less-damaging process in the first place. Another thing to consider is different movement designs warrant different numbers of jewels. An automatic movement will have additional moving parts that would require more jewels to reduce friction. The automatic movement works are under heavy wear and tear, as the rotor spins almost constantly to transmit power to the mainspring.
Talking about sapphire the crystalline nature of the stone lends itself to very fine polishing. The sapphire surface has excellent oil and lubricant-retention ability. An excellent example of that are the Bulova jewel automatic watches of the 50s and 60s, which have proven their jewelled reliability, and have stood the test of time, offering accuracy for over 50 years, despite never having been serviced.
In , years after the first patent for jewel bearings, the use of functional jewels in watchmaking was standardised by the International Standards Organization ISO. A mechanical movement is composed of moving parts, such as gears, wheels and pinions. These parts rotate on pivots, the vertical axes crossing the wheel. However, one has to consider that, for example, the fourth wheel of a watch makes a full circle on its axis, once per minute, making 1, full rotations a day or 5,25, full rotations a year.
This is why it is harmful to insert the axis of such a wheel directly in the main-plate of the movement — considering the metal-vs-metal friction. Even with modern lubricants, the axis can slow down the movement of the wheels — ruining the accuracy of the watch — and at some point, wheels will simply get blocked.
The solution — jewel bearings, which allow low friction with metal pivots. They also possess excellent temperature stability and are acid-resistant. The pivots and jewel bearings of the balance wheel are especially fragile and would often get damaged under impact. Cap jewels, also known as end stones or capstones, work just as the others do.
However, they require a second or outer jewel that sits at the tip of the gear shaft. This results in a few functional effects. Firstly, it ensures lubrication for fast-moving parts like the balance wheel. This is done by forming a small oil reservoir between the two jewels. This type of bearing also keeps the shoulders of the arbour from rubbing against the jewels. If the shoulders of the arbour rubbed against the jewels, it can greatly impact the accuracy of the watch.
Moreover, capstones also keep the arbour from moving unnecessarily up and down during rotation. As its name suggests, the pallet jewels have a pretty straightforward function. They can be described as rectangular jewels. Pallet jewels can also be found at the end of each of the arms of a pallet fork.
It serves as a conjunction point between the two. Roller jewels usually have a caved upper side while its lower side is flat. They are usually found inside the pallet fork of a movement.
However, most watch movements have 17 jewels. At that point, a watch can already be considered fully jewelled. But as a rule of thumb, the more complications a movement has, the more jewels it should have.
A movement with 17 jewels has the following usage in various areas of a movement:. Having 21 jewels only usually means that it has more cap jewels or capstones to keep the jewels from moving and for a more efficient function.
Extra capstones can usually be seen on high-quality timepieces. There are two sides to this. One must remember their aforementioned function, and that is to minimise the friction between the mechanical parts of a watch. And as you know, more complications mean more parts. Therefore, it only makes sense that it has more jewels. By complicated watches, we mean watches such as a perpetual calendar watch, a tourbillon, or a chronograph.
There are other features that make a watch complicated such as dual time or GMT, or even power reserve indicators, as well as moon phases. Name an extra feature on a watch and it will fall into that category. The more complicated a watch gets, the more jewels it requires for more lubrication and less friction when moving. A lot of them can also be found in mid-tier and even entry-level watches.
If anything, the number of watch jewels in a movement only shows how complicated or intrinsically engineered a mechanical movement is. In some cases, more jewels also mean thinner movements, therefore, thinner watches. So, if you ask us, the answer is no. Having 2, components, it only makes sense that its jewels also exceed in number. It has 6 functions for time, 7 perpetual calendar functions, 8 Hebrew calendar functions, 9 astronomical calendar functions, a lunar calendar, a religious calendar, 4 chronograph functions with 3 column wheels for each, 7 alarms, and 8 Westminster carillon striking function.
It also has a power reserve indicator, a power reserve indicator for the striking train, a crown position indicator to easily verify the mode it is on, dual-barrel winding, a time setting that lets two positions and directions function, as well as a secret mechanism to wind the striking train.
The quickest answer is no and it rests on various factors. Among those include the fact that the jewels in a watch are actually man-made gems. The ETA Calibre proves to be one of the most popular movements in the industry. These pivots are normally lightly oiled for the parts to run smoothly, but in addition to oil, small Rubies and Sapphires are sometimes utilized. Since it's so hard, the surface of a ruby serves as a sort of natural lubricant and essentially becomes a bearing.
Original watchmakers used mined precious rubies, but nowadays the actual crystals used in watch movements are mainly synthetic. The jewel count refers to the number of pivots with inset rubies - or "jewels"!
When you see 7 or 17 jewels, the particular movement you're looking at features that number of jewel-inset pivots. There are many different factors to consider that speak towards determining quality, and although not always the case, higher jewel counts are typically indicative of premium craftsmanship.
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