All About Jewels
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Rubies and Sapphires
Watch companies used semi-precious gems like garnets, rubies and sapphires as bearings to reduce friction for the hardened steel pivots of the gear train, which was a big upgrade over softer bronze bushings.
Learn the types of jewels, their function and location, and how to determine the jewel count of an unmarked watch just by looking at it.
Types of Jewels
Hole and Cap
The two primary types are hole and cap jewels, and both have precise functions on the balance assembly and in the gear train of a watch.
Loose jewels are are those that have not been mounted in a setting.
Think of the difficulty involved in making these tiny parts after mining the raw materials and somehow cutting them into usable shapes.
Jewels in Settings
Jewels of both types could be mounted in a setting made of bronze, brass, amalgams of either, and even gold. The setting was a ring with an internal shoulder to hold the jewel in place, while a press crimped the metal edges of the setting over the jewel, permanently securing it.
Diamond Cap Jewels
Diamonds were used as decorative cap jewels on the balance staff and occasionally on the escapement of the very highest of grades that a factory had to offer. While they likely increase the value of the watch, the diamonds themselves do not contribute to its accuracy.
Which watch had the most? Waltham's legendary 16-size Riverside Maximus came with 3 pairs of diamond cap jewels, for a total of six.
Roller Jewels
Sometimes referred to as the impulse jewel, this stone trips the pallet fork in the opposite direction by every single arc of the oscillating balance wheel, absorbing millions of impacts during its service life.
The roller jewel is mounted to the roller table of the balance wheel with shellac, a slightly gummy resin secreted by the female lac bug.
For more information on roller tables visit the Tutorials page.
Pallet Stones
These paired stones were also mounted with shellac to the pallet fork, halting the gear train and pushing the balance wheel through its arcs.
It's the precisely angled and polished faces of those two stones, driven by the mainspring, that impels the balance wheel into its next cycle.
Jewel Functions
Hole Jewels
Hole jewels were used as bearings for polished steel pivots that generated very little friction when properly oiled and maintained, relying on the flat face to control endshake, which is vertical travel.
They were made from industrial-grade precious stones, so they were much harder than the steel gear train pivots but even more brittle.
Capped Jewels
Cap jewels provide a rebound surface for the pivot tips, eliminating the need for the flat surface found on hole jewels. Balance wheels and the escapement components use hole and cap jewels in tandem, which trap the staffs by their pivot tips. Capped pairs generate less friction because smaller surface areas are in contact with each other.
Escapement Jewels
Jewels were also used in lever escapements, which was the eventual design choice of most American watch companies. The roller jewel, mounted on the balance wheel, gives the impulse to the pallet fork, alternately locking and releasing the entry and exit pallet stones. This allows the escape wheel to rotate at a specific rate one tooth at a time, which gradually lets down the mainspring until it's completely spent.
Jewel Settings
Bushings
Bushings are not jewels.
They are simply holes drilled into both upper and lower plates for the escapement, gear train, and mainspring arbor. The contact between all of the parts is metal on metal, and unless maintained properly the bushings will enlarge and become oval over time, ruining the watch.
Press-Fit
Holes with stops were milled into the plates, a loose jewel dropped into the hole, and then the plate metal was rolled over the edges of the jewel, trapping it in place. These are not easily replaced and must be shattered to remove them before a new jewel can be fitted.
Flush Friction
These jewels were mounted in settings and then seated from the inside so they can't fall outward, fabricated with precision to end up flush with the plate surface. Friction keeps the setting in place, so they're easily changed if necessary. This is also known as an "interference fit".
Flush Screw
Unlike friction-fit jewels, these kinds of settings were almost always screwed in from the top side of the plate, though there are exceptions. The settings were carefully milled flush with the plate so they couldn't interfere with the oscillation of the balance wheel on full-plate designs.
Raised Screw
Sometimes called "smokestack" jewels, these settings were almost always gold and were again screwed in from the top. The purpose of raised settings was partly for show, but they also did a better job of retaining oil so that it didn't migrate onto the plates, staining them.
Raised Friction
These are also raised for oil retention but are pressed in from the inside of the upper plate to prevent them from falling outward. They are used for a clean look on only the higher grades and are almost always gold. Any cap jewels, which must be installed first, are not a snug fit and are kept in place by the friction-fit hole jewel, installed second.
Jewel Locations
There are just seven primary components in the gear train of any American railroad-era watch, no matter the size or model, making for seven jeweling locations. The exceptions are 5th pinion designs, made by Illinois and Aurora, which convert hunting movements to open-face.
- The mainspring barrel that provides power
- The center (second) wheel, which drives the hands
- The third wheel between the center and fourth wheels
- The fourth wheel, which holds the seconds hand
- The steel or bronze escape wheel
- The pallet fork with entry and exit stones
- The balance wheel, which carries the roller jewel
The pallet fork utilizes six jewels (two pairs of hole/cap and two stones) on a higher-count watch, while any balance wheel utilizes five jewels (two pairs of hole/cap and a single roller jewel).
5th Pinion Watches
An Extra Idler
A few companies that had produced hunting movements with a standard gear train chose to modify their existing design to achieve an open-face watch, rather than go back to the drawing board and come up with a completely new model.
The 4th wheel on a hunting movement (yellow arrow) carries the second hand, and to convert it to open-face the factory simply added an extra idler (red arrow) with the same pinion leaf count 90 degrees away so that it was opposite the winding stem and mounted the seconds hand there.
5th pinions can also be jeweled, singly and in pairs, adding to the count.
7 Jewels
The Lowest Count
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones (1 entry and 1 exit)
- 1 roller jewel
Seven jewels was the lowest total for the vast majority of American pocket watches, and is the basis for all higher counts. There are no jewels on the gear train and the regulator is usually a simple one.
Metal on Metal
The purpose of hole and cap jewels was to reduce friction between the gear pivots and the plates in which they rotated. In a 7-jewel watch the entire gear train used bushings instead of jewels. Over time the pivots and the bushings can wear badly, especially with poor maintenance, and once the plate bushings become enlarged the watch is ruined.
The Fake Jewels
Several companies, such as Seth Thomas and NY Standard, produced 7-jewel watches with glass cap "jewels" on top of every pivot, along with false jewel counts and railroad motifs stamped on the plates.
Underneath are standard metal bushings, though the glass caps may serve a purpose by keeping a certain amount of dust out of the pivots. The micro-regulator on the balance is functional.
11 Jewel
Upper Plate Only
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 hole jewel for the pallet staff, the escape wheel, and the 3rd and 4th wheels, for a total of four
All the jewels are visible on the upper plate, with none under the dial. The tip-off between an 11 and a 15-jewel watch is that the lower count will usually have only a simple regulator.
12 Jewels
Upper Plate Only
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 hole jewel for the pallet staff, the escape wheel, and the 3rd, 4th and center wheels, for a total of five
Again, all of the gear train jewels are on the upper plate, with corresponding metal bushings on the pillar plate.
15 Jewels
Everything in Pairs
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, the escape wheel, and the 3rd and 4th wheels, for a total of eight
The tip-off between a 15 and an 11-jewel watch is that the higher count will usually come equipped with a micro-regulator.
17 Jewels
A Fully Jeweled Watch
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, escape wheel, and the 3rd, 4th and center wheels, for a total of ten
All the necessary components are jeweled, except for the mainspring, which rotates too slowly to generate any appreciable friction.
19 Jewels
Externally Jeweled Barrel
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, escape wheel, and the 3rd, 4th and center wheels, for a total of ten
- 1 pair of jewels for the external mainspring barrel
External barrel jewels make it easier to wind the watch.
Internally Jeweled Barrel
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, escape wheel, and the 3rd, 4th and center wheels, for a total of ten
- 1 pair of jewels for the internal mainspring arbor
Arbor jewels smoothly let down the mainspring, increasing accuracy.
Unjeweled Barrel
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, escape wheel, and the 3rd, 4th and center wheels, for a total of ten
- 1 pair of cap jewels for either the pallet staff or the escape wheel
For more info on the different types of barrels, visit the Tutorials page.
21 Jewels
Escapement Cap Jewels
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, escape wheel, and the 3rd, 4th and center wheels, for a total of ten
- 1 pair of cap jewels for the pallet arbor and the escape wheel, for a total of four
Internally Jeweled Barrel
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, escape wheel, and the 3rd, 4th and center wheels, for a total of ten
- 1 pair of cap jewels for either the pallet arbor or the escape wheel
- 1 pair for the internal mainspring arbor
23 Jewels
Escapement Caps and a Jeweled Barrel
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, escape wheel, and the 3rd, 4th and center wheels, for a total of ten
- 1 pair of cap jewels for the pallet arbor and the escape wheel, for a total of four
- 1 pair for the mainspring arbor
Gear Train Caps Only
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the pallet staff, escape wheel, and the 3rd, 4th and center wheels, for a total of ten
- 1 pair of cap jewels for the pallet and escape wheel, and 1 on the upper 3rd and 4th wheels, for a total of six
Jeweled Banking Pins
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the gear train, for a total of ten
- 1 pair of cap jewels for the pallet arbor and the escape wheel, for a total of four
- 1 pair of jeweled banking pins
Non-Functional Jewels
Jeweled banking pins were to artificially inflate the count and did not increase accuracy. This design is found on the 16-size Howard Series O.
Why are they non-functional? Because there is no friction between the pallet arm and the banking pins. The pins act as stops for the pallet as it swings back and forth, producing the familiar "tick-tock" sound.
24 Jewels
Gear Train Caps Only
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the gear train, for a total of ten
- 1 pair of cap jewels for the pallet arbor, escape and 3rd wheel, and 1 on the upper 4th wheel, for a total of seven
24-jewel models are somewhat rare, with few factories making them.
Caps and a Jeweled Barrel
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the gear train, for a total of ten
- 1 pair of cap jewels for the pallet arbor, escape wheel, and 3rd wheel for a total of six
- 1 hole jewel for the upper mainspring barrel
25 Jewels
Gear Train Caps and a Jeweled Barrel
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the gear train, for a total of ten
- 1 pair of cap jewels for the pallet arbor, escape and 3rd wheel, and 1 on the upper 4th wheel, for a total of seven
- 1 hole jewel for the upper mainspring barrel
Only four American companies made 25-jewel watches as regular production pieces - Columbus, Illinois, Rockford and Seth Thomas.
Who made the fewest? The Rockford Watch Co, with only a dozen.
Who made the most? Seth Thomas, with roughly 720 in all variants.
26 Jewels
The American Maximum Count
- 2 balance staff hole jewels
- 2 balance staff cap jewels
- 2 pallet stones
- 1 roller jewel
- 1 pair of hole jewels for the gear train, for a total of ten
- 1 pair of cap jewels for the pallet arbor, escape and 3rd wheel, and 1 on the upper 4th wheel, for a total of seven
- 1 pair of hole jewels for the mainspring barrel
Illinois was the only company to offer a 26-jewel watch in greater numbers, and roughly 250 of those were produced in three grades: Bunn Special, Benjamin Franklin and Pennsylvania Special.
Pennsylvania Special photo courtesy of Jones & Horan.