Here is an article partially based upon work published by Professor J.C. Nicolet...


"The History of Jeweled Pivots in Watches"


BACKGROUND

The important parts of a mechanical watch are mainly those that move, i.e. gear trains, the balance and the escapement. In early times, the fine pivots of these pieces turned directly in holes drilled into two brass plates separated by pillars.

In order to facilitate assembly and repair, the upper plate was later replaced by separate elements, called "bars" (also "bridges" or "cocks" depending on the number of supports).
The lower brass plate (called "bottom plate" or “pillar plate”) was drilled with small holes in which the other ends of the pivots turned. These holes also contained small oil sinks from which the oil flowed into the holes to lubricate the pivots.

With time, though, dust from the air collected in the oil sinks. This resulting mix of oil and dust formed an abrasive substance which acted like sandpaper, slowly filing away the softer brass of the plate and to some extent even the harder steel pivots. With continued use, the abrasive action of the oil-dust mixture working in concert with the turning action of the pivots caused the holes to become oval. Then the watch would start to run erratically, and finally stop.

These observations led watchmakers to look for a bearing material harder than brass that would withstand more wear and tear from the pivots. The substance they turned to was the ruby, except for diamond, the hardest known substance at the time.

WATCH JEWELING HISTORY

The use of the ruby in watches goes back to 18th century England (at the time the cradle of leading edge horology) where watchmakers first had the idea of using small ruby pellets (called jewels) as bearings for the pivots of the balance.

The key technique of drilling the ruby to accept a pivot was invented by a Swiss optician and astronomer, Nicolas Fatio, who went to England in the hope of exploiting his invention. He tried to obtain a "royal privilege" for his technique which they wrongly claimed was already in use.
In the end, Fatio did not receive the privilege, but other skilled craftsmen set about using his methods to drill ruby pellets for the watch trade.

In those days watch jewels were made from second-rate stones discarded by the jewelry trade. The Fatio technique for precision drilling of the rubies gave the British watch industry a marked advantage over continental horology for about 20 years. After that, French watchmakers such as Abraham-Louis Breguet acquired the trade secrets by luring English craftsmen to work for them in France.

For many years, the manufacture of jeweled watch pivots remained a costly, labor-intensive process, which meant that they were used exclusively in very high quality watches. Slowly their manufacture became more mechanized and their prices more accessible, akin to developments in other aspects of watchmaking.

SYNTHETIC RUBIES

A further decrease in price accompanied the creation of synthetic rubies, based a method developed in 1902 by Auguste Verneuil, Professor in Paris' Conservatoire des Arts et Métiers. In the industrial fabrication process, the basic component alumina (aluminum oxide) undergoes a series of operations, i.e. purification, heating, fusion and crystallization, which results in pear-shaped pieces of man-made ruby called a boule. Chromium oxide is added to get the red color of natural rubies.

The large-scale manufacture of rubies created an abundance of these synthetic stones, more homogeneous in quality than what is typically found in nature. The jewelry trade still takes most of the stones, but there is still plenty low cost rubies left for watches. In watchmaking, the cost of the rubies was reduced to the labor needed to drill and set them, as the cost of the raw material was relatively low.

Having said this, it must be noted that from beginning to end-product, about 90% of the ruby is destroyed, with only the remaining 10% usable for watches. Up until 1930, the ruby pellets were fitted into settings of gold or brass, which in turn were screwed down to the plates, but later evolution of more precise plate machining methods allowed the technique of driving (pressing) them directly into the plates, thus lowering production costs even more.

JEWELING WARS

In the mind of the public, the idea that watches contain jewels give them a certain added prestige value. Manufacturers were quick to exploit this belief and started to add superfluous stones to increase the prices of their products. The term "upjeweling" was an American term coined to refer to this dubious practice which was fairly widespread in the U.S. around the turn of the 20th Century. It was finally abolished by the U.S. Customs authorities who disallowed "upjeweled" imports from entering the country. There are some, however, who suggest that their real motives may have been less noble and that this was merely a kind of camouflage protectionism for the U.S. watch industry.

Today, Swiss watchmakers no longer use this questionable practice and their advertisement is not based on the number of jewels in a movement. The total number of rubies, i.e. "jeweling", can vary. In a simple hand-wound mechanical watch, the number of jewels needed to be "fully jeweled" varies from 17 to a maximum of 19. Higher jewel counts than 19 are achieved through the use of cap jewels on the escapement and train pivots.

To sum it all up, having jewels in a watch is certainly a factor that adds to its overall quality. They are indispensable for the long-life and correct functioning of a good quality watch.

This interesting paragraph is from an article published in 1949 in Consumers' Union. The article concerned the value or quality of various watches then on the US market. Very interesting article.

The site of the article is:
http://filebox.vt.edu/users/zbortolo/watches/Page_2.html

One of the interesting point in the article, which it should be emphasized was published in 1949, is its rating of Swiss vs. American-made watches, and its statement that, at that time, jeweled pocket watches were more reliable for accuracy and durability than wristwatches.