Watch Terminology Dictionary

One of the components that make up the balance wheel. The main materials are brass, nickel, and beryllium alloy. The first two are inexpensive and easy to process, but they are easily scratched and their expansion rate is easily affected by temperature. For this reason, Swiss and German mechanical watches often use a more stable beryllium alloy. When used together with the hairspring, it gives the watch a certain level of accuracy, but if the balance wheel itself experiences air resistance or uneven weight due to poor processing accuracy, this can worsen accuracy. Furthermore, if the expansion rate changes with temperature, it can cause the watch to lose or gain time. Glucydur, made by Nivarox, is a type of beryllium alloy, but because it is a registered trademark, it cannot be used by any company other than Nivarox.