METEORITE DIALS
Various meteorite deposits are used in watchmaking. However, these are always iron meteorites (5% of meteorite falls), belonging to the octahedrite category. They are composed, on average, of 90% iron, with a variable percentage of nickel, and possibly other elements (iridium, chrome, gallium, etc.). The first manufacturing step involves extracting a cylinder from the raw meteorite through coring (sawing or electrical discharge). The obtained cylinder is then cut into slices with a thickness slightly greater than the final dial plate. Subsequently, its thickness is reduced to refine its surface state.
At this stage, the meteorite resembles an ordinary piece of iron. By exposing the meteorite to nitric acid (immersing the dial insert), the unique crystalline structure of iron meteorites is revealed. It unveils fine parallel lines that form characteristic geometric patterns known as Widmanstätten patterns or Tomson structures. Due to its iron composition, the meteorite is prone to oxidation (rust). It is generally protected by electroplating treatments (rhodium plating, gold plating, etc.) or by physical vapour deposition (PVD, DLC, etc.).
The dial base (usually made of brass) is mechanically compartmentalized to precisely position and index the meteorite insert(s). The thickness of the meteorite can vary depending on the specifications of each dial, but it is often between 0.20mm and 0.40mm for a dial with a total thickness of 0.80mm for a dial and a base plate. Once the meteorite insert and the base are completed, the meteorite insert is glued to the brass base. Any application of indices, stamping, and other features can be easily accomplished traditionally without posing any difficulties.