What are jewels?

[phoneman]

Hi. I'm kind of new to horology and work only on clocks. I have always wondered what jewels were in watches, and or, clocks. What are their functions also? Thanks.
Bill

[phoneman]

Hi. I'm kind of new to horology and work only on clocks. I have always wondered what jewels were in watches, and or, clocks. What are their functions also? Thanks.
Bill

[Kate N]

Hi Bill,
Jewels are exactly what they sound like--- semi-precious or precious stones. Today, these jewels are lab-created, but, in the past, they were natural jewels. There are several different types, including plate jewels, cap jewels, roller jewels and pallet jewels. Their use results in better time-keeping and longer wear, due to the reduced friction. Plate jewels are cut into flat,round shapes, and holed, so the pivots and arbors can fit through them. There are also cap jewels, which are not holed and are used, in addition to the holed jewels, for balances. These limit the up and down movement of the pivot. Roller jewels are long, and extend downward from the roller to enter the pallet fork. Pallet jewels are essentially rectangular, most with 1 end of the rectangle angled, to contact the teeth of the escape wheel. For mechanical watches, generally, the higher the jewel count, the better the watch. Of course, there were manufacturers who took advantage by putting non-functional jewels in watches, to give the impression of better quality. That's my understanding of watch jewels and, if anything I've stated is incomplete or inaccurate, I'm sure the good folks here will add to or correct the info.

[John F]

Watch jewels are small bearings made out of precious and semi-precious stones, often rubies, that are used to reduce friction and wear. The gears of a watch are fitted onto arbors (or axles), and the end of the arbors fit through and turn in a hole in the middle of the jewel, which is attached to the watch plate. Some arbors may also turn in unjeweled holes in the watch plates, but in such cases the potential for friction and wear from the metal-on-metal contact is the greatest.

All "jeweled watches" have 7 jewels in the balance works: 2 bearing jewels and 2 "cap" jewels that hold the balance staff in place, 1 jewel on the balance wheel, and 2 jewels in the lever that engages the escape wheel. (A "cap" jewel has no hole, but is fitted over the end of a jeweled bearing and helps to keep dust out). A "fully jeweled" watch has 17 jewels - 7 in the escapement plus 5 pairs of jewels on the other arbors.

Additional jewels may be also used on other moving parts of the watch, such as on the barrel. Sometimes additional cap jewels are used, as well. After the 7 jewels in the balance works, jewels are commonly fitted in pairs - one on the top plate and one on the bottom plate - which is why watches usually have an odd number of jewels. If a watch has more than 17 jewels, the additional ones are typically cap jewels.

There are always exceptions to this configuration, but this is commonly what you'll see.

(I see Kate already answered - man, do I type slooooowly!)

[Kent]

Hi Bill:

To add to what the others have said, the jewels in a watch were, for the most part, the bearings. These were industrial jewels, not at all gem quality. They provided hard, low-friction, wear-resistant surfaces. The basic number of jewels in a “jeweled� watch is 7, after which, jewels were usually added in pairs (one exception is the upper center jewel in 16-jewel watches). From the 1860’s through the 1880’s, watches were said to be “Fully Jeweled� if they contained 15 jewels. Moving upward from 15-jewels, American watch companies almost always added the 16th jewel as the Upper Center Jewel (http://photos15.flickr.com/20386597_b1d130c3e7_o.jpg) (an exception doesn't come to mind) and the 17th jewel as the lower center jewel (this generally isn't considered necessary and many high grade European watch makers didn't bother with it). Adding additional jewels, up to 19, usually produced a demonstrable improvement in timekeeping accuracy. In adding 2 more jewels to bring a watch up to 21, the increase in accuracy was more theoretical than practical. Any number of jewels over 21 usually failed to gain any additional timekeeping improvement. It should be noted that additional labor to properly adjust a watch did more to improve accuracy than adding jewels above 16 or 19. In fact, the Elgin grade No. 240 B.W. Raymond, a 19-jewel, 18-size, Veritas model (three-quarter plate) movement, is considered by quite a few people to be one of the best timekeepers ever made.

There is an excellent discussion on watch jewels on Wayne Schlitt's Elgin Website at:
www.elginwatches.org/help/watch_jewels.html
To view, go to the Elgin Watch Collectors Site Home Page at elginwatches.com, then copy and paste the address in your browser's address bar and click on 'Go'.

Several glossaries, or descriptions, of watch terms are available online:
John Duvall's Components of a Pocket Watch (http://nawcc-***-mb.infopop.cc/helphand/pwc/pw01.html),
The Time Zone has an excellent Glossary of Watch Parts (http://www.timezonewatchschool.com/WatchSchool/Glossary/glossary.shtml),
The Horology WebRing offers The Watch-Collector's Paradise (http://www.datacomm.ch/rbu/index.html),
The Watch Cabinet has A Brief Glossary of Technical Terms (http://www.horologia.co.uk/watchglossary.html).

Either look up jewel, or just scan through the pages to see how the jewels are arranged in a watch. Keep in mind that the roller pin and the pallets are shaped jewels. Also, hole jewels and cap jewels often have brass or gold settings. So, if you see a gold ring identified as a jewel, look carefully, there'll probably be a clear jewel set in the ring.

Good luck,

[phoneman]

Thanks to everyone for the great info. I won't feel so stupid now when I'm reading descriptions of pocket watches in my copy of the bulletin.
Bill

[Kate N]

Kent, I always enjoy your posts, as I learn something with each one. Can you enlighten me a bit about your statements regarding the 16th and 17th jewels not being necessary (perhaps I misunderstand and you're only referring to the 17th the lower center jewel), but that jeweling up to 19 jewels noticably improves timekeeping. I would like to know why the upper center jewel would improve timekeeping, but the lower center wouldn't, if that's what you meant. Please be assured that I'm not doubting you, but am very interested in learning the reason behind this.

John, I probably started typing 10 minutes before you did--I'm that bad at it! :smile: For me, I know I'd much rather receive 2 or more similar replies than none at all.

[Don Dahlberg]

Kate N,

Kent may well respond to your question, but I am going to throw in my $0.25.

There has long been a debate as to what is a "fully jeweled watch". I think it is more a question of deminishing returns.

Jewels are first put where there is the most wear. This is the fast moving escapement resulting in a 7 jewel watch. Slower moving wheels are not jeweled as less necessary.

As more and more jewels are added they are added to ever slower moving wheels and/or to the bridge side pivots (rather than the pillar plate). Some watches were jeweled up to the third wheel on the bridge side and not jeweled on the pillar plate. Some say this was to make a 11 or 13 jewel watch look like a 15 jewel watch, since you can only see the bridge jewels without taking the dial off. Others say this was because the watch seldom ran dial down. In the dial up position the pivot would be resting on the bridge jewels. Of course, in a pendant position, the wheel would be riding on a jewel on one end and on metal on the other end. A sixteen jewel watch again would have the center wheel jeweled on the train bridge, but not the pillar plate.

Once you have 17 jewels, all the wheels except the mainspring barrel have been jeweled on both ends. If you are going to have 19 jewels, you have two places left to do some good. You can jewel the mainspring barrel, or you can go to olive hole/cap jewels pairs on the escape wheel. The former solves a slow wear problem that appears in mainspring barrels. The latter (use of olive hole jewel, cap jewels and conical pivots) decreases the friction on the escape wheel compared to square shoulder pivots and hole jewels. This gives the watch better isochronism, that is it runs closer to the same rate at full mainspring wind and half mainspring wind. At 21 jewels we can put cap jewels on the pallet arbors and 23 we can throw in the mainspring barrel arbors.

Do 23 jewels allow the watch to run more accurately and longer with less wear? The answer is yes. Of course it will add to the initial cost and to the cost of maintaining the watch. It is harder to clean a 23 jewel watch than a 17 jewel watch, because you have to take the jewels out to clean between the sandwiched jewels.

Does a Porsche run better than better than a Ford Torus? Yes, but the Porsche requires more care to keep running that way. At what point is it not worth the extra cost? It depends on how fast you want to go.

Since railroad requirements were only 30 seconds per week, a good adjusted 17 jewel watch (like the Hamilton 972) was all that was really needed. Jeweling the mainspring barrel at least added to the longevity of the watch. Beyond that it was just bragging rights.

Don

[Dr. Jon]

Don

You are technically correct, something Web Ball tried to make clear in his early catalogs but as the public started to associate jewel count with quality the makers got locked into a price structure that prohibited them from doing the adjustments needed for good performance on watches with less than 17 then 19 jewels. This is reflected in later Ball correspondence posted by Jeff Hess.

Thus the jewel count versus quality became a self fulfilling statement for American Watches.

[doug sinclair]

Bill,

Another way of describing the presence of jewels and their effect on friction shows in the Waltham material catalog of 1948. I use for example the 1899-1908 model which was made with anywhere from 7 to 23 jewels. The available mainspring strengths to fit these movements ran from .015 to .019 mm (thick), depending on the number of jewels in the watch that the spring was required for. The .019 for the 7 jewel, up to the .015 for the 23 jewel. The extra jewels in the movements in the examples given helped in reducing friction, retaining oil, thereby contributing to greater accuracy, and a watch that had the potential to perform better, for longer. If you fitted the strong spring to the 23 jewel watch, you had a real problem. Likewise the weak spring to a worn 7 jewel watch. I have read that the jewels are approximately 90 times harder than the pivots that run in them, and they will take a much higher polish than a metal bearing as a result of that hardness.

You might well ask if a 17 jewel watch is considered fully jewelled, what would be the advantage of adding 6 jewels to produce a 23 jewel watch? In the 1908 model Waltham, two of the extra jewels went to the mainspring barrel so the the first wheel (main wheel) was jewelled, and four jewels became cap jewels on the pallet arbor pivots and escape wheel pivots which allowed the use of concave (sometimes erroneously called conical) pivots instead of square shouldered pivots. This reduced friction even further in the higher jewelled model as the TIP of the pivot running on the end-stone became the thrust bearing, rather than the square shoulder of the pivot running on the flat surface of a hole jewel.

[Kent]

Kate:

My apologies for not being clear about it, its the lower center jewel that really isn't necessary. The top center hole of a watch is subject to a relatively large amount of force. Poorly maintained watches of 15-jewels, or less, tend to exhibit wear in this hole. Thus, adding an upper center jewel reduces the friction and resultant wear associated with the higher forces. However, the lower center hole is relatively free of force, and hence, doesn't require a jewel.

It's not only the high grade Swiss watches that don't have the unnecessary (well, very much less necessary) lower center jewel. An 1889 Columbus Ad (http://southbendhorology.com/movements/columbus/c_1889.jpg) on Frank Kusumoto’s South Bend Website (http://southbendhorology.com/) shows that the Columbus the 18-size, grade No. 18 at the top of their line was a 16-jewel watch. In the early 1890s, Illinois' 18-size, 16-jewel Bunn (http://static.flickr.com/39/74984426_e989514094_o.jpg) (having no lower center jewel) was the highest grade watch in their line. In 1895, the best 18-size Elgin watch was the grade Nos. 149 & 150 (hunting-case and open-face), 20-jewel movement. See: <span class="ev_code_brown">www.elginwatches.org/scans/elgin_ads/1895/m_ElgnRRTS.html</span>

<span class="ev_code_blue">To view, go to the </span><span class="ev_code_brown">Elgin Watch Collectors Site Home Page</span> <span class="ev_code_blue">at</span> <span class="ev_code_brown">elginwatches.com</span>, <span class="ev_code_blue">then copy and paste the address in your browser's address bar and click on </span>'Go'.

[Robert Sweet]

Bill,
The link below is an excerpt from Technical Manual 9-1575, (War Dept. Tech. Manual), 6 April 1945.

It about the same information, just in different format.

Robert

Jewels (excerpt) TM 9-1575 (http://static.flickr.com/40/75037922_be349684ee_b.jpg)

[Kate N]

Many thanks for the informative replies! I've learned a few things and got some good websites to peruse, also. It's great to know that so many people are willing to share their knowledge here.
Kent, there's no need to apologize--you promptly clarified things. A very strong part of my interest in watches is the fact that I enjoy learning about how things work and I get tremendous satisfaction from repairing things. The better I understand how a thing works, the simpler it becomes to diagnose problems.
Thanks, again, to all who responded.