In watchmaking, curvature is not an aesthetic detail added after the fact: it is a design choice that conditions readability, the profile in the case, and the optical behavior of the piece on the wrist. You find it applied to different components — crystal, case, dial, bezel, integrated bracelet — and in each of these contexts it has specific technical reasons.
The domed crystal, also called domed or cambered, is the most familiar form. The convexity toward the outside reduces the peripheral distortions typical of the box profile with right angles and improves light entry onto the dial. The box-type crystal, on the other hand, exaggerates this curvature on both surfaces, creating a pronounced depth-of-field effect, but paying a price in readability at the edges — lateral distortion is real, not an impression. Anyone who has worked on vintage watches from the 1960s knows this: beautiful when stationary, less comfortable on watches with dense circular scales.
Double curvature is a more sophisticated solution. Audemars Piguet's Code 11.59 is the most debated example: concave inside, with a convex vertical curve on the outer surface from 6 o'clock to 12 o'clock. The optical effect is singular when viewed frontally, with controlled but visible distortions from lateral angles. It is not a design flaw: it is the declared consequence of that geometry. Material matters: hesalite (acrylic) lends itself to more pronounced curvatures than sapphire, which offers greater resistance to machining and imposes wider minimum radii of curvature.
The curved-profile case — such as the ellipsocurvexa concept or Greubel Forsey's Convexe design — follows the anatomy of the wrist on the longitudinal plane. This conformation is not merely aesthetic: it reduces dead space between case and skin, lowers the perceived center of gravity, and distributes weight better across wrists of varying cross-section. In integrated bracelets, progressive curvature across multiple axes — as in the Ming 56.00 — serves to eliminate the points of localized pressure that form when a rigid bracelet meets a wrist with non-uniform curvature.
The domed dial belongs to a construction tradition that has almost been lost with the transition to ETA movements in the 1980s: it required precise dialogue between the shape of the dial and that of the crystal above it. When both are curved in agreement, the visual depth is authentic. When the dial is flat under a domed crystal, the effect is simulated. From the bench, you can see it immediately.
Regarding the buckling phenomenon — the curvature that precedes the abrupt snap in the opposite direction, adapted by Girard-Perregaux in the silicon blade of the Constant Escapement — I have no direct disassembly experience: I simply report what has been documented by the manufacture.