CHPTR_Δ Black Diamonds (Chapter Delta) is the first BA111OD manufacture watch complication, a unique timepiece that represents time in a revolutionary way.

Developed with renowned watchmaker Olivier Mory, it introduces an entirely new approach to time display. Instead of simply rotating a hand around a central axis, the movement was conceived to roll a satellite hour wheel around a fixed central hour wheel. This creates a deltoid trajectory, meaning the tip of the hour hand traces a triangle, a world premiere in watchmaking. With its asymmetrical reading of time, CHPTR_Δ challenges convention and offers a bold new way to experience horology.

In this black diamond-set execution, the watch takes on an even more singular presence, enhanced by a bezel set with natural black diamonds. This refined detail intensifies the depth, contrast and sophistication of the design, giving one of BA111OD’s boldest creations an even more precious and distinctive expression.