OK, here goes.........

A quartz watch works by measuring the frequency with which the crystal vibrates when subjected to electric current. The crystal generally vibrates at 32,768Hz (although other frequencies are available) and the watch will therefore tick once for every 32,768 vibration cycles.

However, the rate of vibration is affected by temperature, and generally crystals are only going to be accurate at around 27 celsius. The rate of variation isn't much, but it adds up! The good news is that the variance can be predicted - i.e. the variance can be calculated based on the actual temperature.

Breitling's SuperQuartz, and virtually all other modern compensated quartz technologies are thermo-compensated. This involves a temperature sensor and some funky computing to adjust the rate at which the watch ticks.

For example, if the temperature is a constant 20 celsius then the computer chip can look up the rate at which the quartz slows down with a drop of 7 degrees and make the watch tick more frequently than every 32,768 cycles to compensate for the slower vibrations and prevent teh watch from losing time.

In the real world only one tiny adjustment is necessary every few minutes.

So comprehensive, it's worth reading twice! (Dial-up playing up again, Roff? )

According to the article, the Breitling superquartz movements use the same technique as the ETA thermoline line

The Omega was accurate to 12 seconds per year and the Citizen to 3 seconds per year. The difference in accuracy between the Omega and the Citizen was kind of a moot point, IMHO, because both required yearly battery changes.

///M