2009 Momentum - Glashütte Original

Crystal clear
The synthetic corundum that is found both
in a watch’s movement as ruby bearings
and covering the dial as sapphire crystal
are actually man-made, created using a
clever process that imitates nature
By Elizabeth Doerr
T
here is a natural mineral that is irreplaceable in a wristwatch: corundum.
And although the average watch connoisseur may not be familiar with
this term, varieties of it such as ruby and sapphire will certainly allow
the reader to picture what it is we are talking about as these in their
natural forms indeed count among the world’s most sought-after precious
stones for decoration purposes. Corundum, however, also possesses
properties that make it the perfect substance for functions of a wristwatch other than
beauty, such as low-friction bearings. Bearings are necessary in a movement when two
parts move against one another, in order to reduce friction.
As early as the 18th century, English watchmakers were creating bearings of genuine ruby
for balance pivots. Combined with lubrication in the form of oil, it excellently reduced
friction. The technique of drilling the ruby, eventually called olive cutting, was invented
by Swiss optician and astronomer Nicolas Fatio de Duillier in 1704. His technique was
emulated by other skilled technicians, including Peter and Jacob Debaufre in England,
who began producing drilled ruby “pellets” for the horological trade. In those days, the
precious stones used for this purpose were second-rate castoffs from the jewelry trade.
At the time, with no better quality available, the main drawback to the
rubies was their cost due to the labour-intensive techniques involved in their manufacture,
a fact that limited the use of jewels to very high-quality watches. Little by little, their
manufacture, which included cutting, polishing and grinding in addition to drilling, became
more industrialized, though inclusions, which naturally occur in any gemstone, also made
them ever less acceptable as a bearing jewel as horological technology progressed.
Fortunately, in 1902 Auguste Victor Louis Verneuil announced that he had discovered
how to duplicate the chemical composition and crystal structure of a natural ruby, publishing
a paper two years later explaining the process for producing synthetic corundum.
Momentum 1· 2009
Photos: Getty, Fotolia
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