Almost every listing says sapphire, and almost every listing is telling the truth. The interesting question is not which material, but which sapphire: flat or domed, single or double AR coating, and whether the seat was cut to match.

Hardness in practice

Sapphire rates 9 on the Mohs scale, mineral glass about 5.5. That means sapphire resists scratches from keys and door handles, and mineral glass does not. It does not mean sapphire is unbreakable — a sharp impact on a hard edge will chip it, and a chipped sapphire cannot be polished out.

Coating is the real differentiator

A sapphire crystal with no anti-reflective coating reflects about eight per cent of light per surface. Double AR coating drops that to under one per cent, and the difference in legibility under a lamp is dramatic. The catch: external AR coating scratches, and a scratched coating looks worse than no coating at all. That is why many high-end watches coat only the inside surface.

Domed versus flat

A domed crystal magnifies slightly at the edges and gives a warm, vintage feel. A flat crystal gives the crispest view of the dial and is more resistant to edge chipping because there is no curved edge to catch. For a modern sports reference, flat is the correct choice; for a vintage build, domed.

What we fit and why

We fit flat sapphire with internal AR coating as standard, because it is the combination that stays legible for the longest time with the least maintenance. Domed sapphire is available on request for vintage references, and mineral is available where a reference originally used it.

If a crystal on a watch you already own is scratched or chipped, we can replace it and pressure-test the case at the same time.