Why Watches Have Jewels
Most people think of jewels as being something that are valuable
because they are so pretty, but their use in watches was, I believe,
the first time that jewels were used for their functional value.
(Well, possibly diamond dust on drill bits was first, I'm not 100%
The jewels used in watches are usually rubies, sapphires (which are
chemically the same as rubies), garnets and diamonds. After around
1900, most of the rubies used were synthetic. Before 1900, the jewels
were either from stones that were too small or had too many flaws to
be used in jewelry. In either case, they really weren't that costly.
There is often a correlation between the price of the watch and number
of jewels, but the jewels themselves are not the cause of this higher
Reducing friction is an extremely important goal in
watchmaking. Jewels have two important properties that help reduce
friction. First, they can be made to be very smooth, and
therefore they let the metal parts slide easily. Secondly, they are
very hard and therefore don't wear down very quickly. The gears in a
watch are carefully designed so that the teeth roll on each other,
rather than sliding. If the axle of a gear wears away the hole that
it sit in, the gear will shift. That means the teeth will no longer
roll on each other and therefore friction will be increased.
Types of Jewels
There are several different types of jewels used in a watch, the most
- Hole Jewels: These are donut shaped jewels that fit over
the gear axles (in watch lingo, the wheel arbors).
- Cap Jewels: These are flat jewels that are placed on the
ends of the axles (arbors).
- Pallet Jewels: These are brick shaped jewels on the pallet
fork that alternately engage and release the escape wheel. The escape
wheel is the gear with funny "boot" shaped teeth.
- Roller Jewel: This jewel is on the large balance wheel that
swings back and forth. It engages with the pallet fork on the end
opposite of the pallet jewels.
The jewels are carefully shaped so that the capillary action of the oil
causes the oil to be drawn toward the gear arbors instead of spreading
out where it doesn't do any good.
Hole and Cap Jewel
Pallet Stone Jewels
Locations of the Jewels
The jewels are located throughout the watch at key spots. The
following are typical locations for the jewels, as shown on the
- The basic 7 jewels are part of the escapement and balance and are
found on all Elgin watches. They include cap and hole jewels for both
the top and the bottom of the balance wheel (total of 4), the two
pallet jewels and the roller jewel.
- The next 8, making 15 jewels, are hole jewels for the fast moving
part of the gear train.
- The next 2, making 17 jewels, are jewels on the center wheel.
- The next 2-4, making 19-21 jewels, are cap jewels on the escape
wheel and the pallet fork.
Some watches, mostly pocket watches, the mainspring barrel will be
jeweled. In order to safely jewel the mainspring barrel, the watch
needs to have a "motor barrel" instead of the more common "going
barrel". (See the the
Watch Mainspring Barrels
web page for more information.) This can bring the jewel count up to
23 jewels, which is the maximum you will normally see on a pocket
Additional jewels are often needed to make automatically wound watches
efficiently transfer the small amount of power generated by moving
your wrist into the power needed to wind your watch. More jewels are
often used for chronograph functions, time repeater chimes, and
date/date displays. Very complicated watches can have over 40
Shock Protection Jewels
The Relationship between Jewels and Quality
As mentioned above, the jewels themselves are not that expensive, but
watches with more jewels tend to be the higher grade and more
expensive. The general public, over the years, have associated lots
of jewels with high quality and some manufactures have taken advantage
of this false connection to fool people by adding non-functional
On a 7 jewel watch, the only jewel that can easily be seen is the cap
jewel on the top of the balance staff. When additional jewels are
added, you normally can only see half of them as the other half of the
jewels are hidden under the watch dial. Some watch companies,
including Elgin, would jewel only the end of the wheel arbors that was
visible, thus making the watch appear to be higher grade than it
Some Elgin documentation claims that 80% of the cost of a watch is
labor. There is certainly some additional labor involved in creating
the additional parts needed to hold additional jewels and to place the
jewels in the watch. However most of the additional labor needed to
create a high grade watch is from making sure that the watch has the
consistency needed to adjust the watch to high tolerances. Additional
jewels can make it easier to get this consistency.
One of the downsides of jewels is that they break much easier than
metal bushings. Most watches made before the mid 1890s had a maximum
of 15 jewels, even the highest grade railroad watches. "Over
Jeweling" a watch was thought to make the watch less rugged so it was
considered, especially by the Swiss, that jeweling the center wheel to
bring the watch up from 15 jewels to 17 jewels was not necessary. The
center wheel does not need to be jeweled to reduce friction because it
moves so slowly. Since the center wheel arbor sticks through to the
dial side of the watch and drives the gears that moves the hands, the
bottom jewel is especially easily broken.
A highly jeweled watch will usually not wear out as quickly as a watch
that doesn't use jewels but, again, jewels are not required to make a
very accurate and high grade watch.
Jewels are added to make it easier to create a high grade watch, but
adding jewels alone will not make a watch high grade and many
high grade watches do not have lots of jewels.
More On Non-Functional Jewels
Rob Berkavicius has written up an excellent article called
83 Jewels Too Many?.
It goes it more details about various ways that watch companies have
added non-functional jewels to watches in order to make their watches
appear to be higher quality than they really are.