Hardware Reference
In-Depth Information
Zirconia
The back surface of Apple Watch needs to be non-conductive, and also opaque to
eliminate crosstalk between the components of the heart rate sensor. That's why zirconia
was chosen as the material of choice. It's a ceramic material that undergoes a heating
process of 2,640° F, which lasts for more than 30 hours; then during the cooling process,
the sapphire lenses for the sensors are added. Finally, a grinding stone is used to create a
smooth finish that feels comfortable against the skin.
