Blued screws are not decoration

Heat polished steel slowly and it passes through straw, then brown, then purple, then a deep blue at around 290 °C. The colour comes from a thin oxide layer that interferes with light — the same physics as an oil film on water.

That layer is the point. It resists corrosion, and reaching it means the steel has been through a controlled thermal cycle rather than simply cut and fitted. Chemical blueing produces a similar colour in a fraction of the time and does none of this.

Why it is the only colour here

Blued steel is the one colour a mechanical watch produces by itself. Nobody chose it from a palette. That is why it is the only colour on this website.