Breget Ring Watch that has Alarm Function with diameter of 2.3 cm

A very unique Yellow Gold Watch in a form of a ring, with Diameter of 2.3 cm.
The Right crown is used for manual winding and alarm reset. The crown on the left set the alarm time.
The alarm is quiet actually as it will energize a small protruding notch to stimulate your finger to alert you as the alarm. is that a genius design!?
It was sold to Prince Alexandre Demidoff on 18 Oct 1836.
HK Snob