Black Bay One 31 | 31mm, Steel, Diamond Blue Dial Calendar which can be seen through

which can be seen through the sapphire-crystal caseback

The Tank Américaine

Since 1860

mirror-like effect

while the case back is stamped with the Constellation Observatory medallion

Black Bay One 31 | 31mm, Steel, Diamond Blue Dial Calendar which can be seen throughThe Black Bay One 31 36 39 41 models bring a unique aesthetic to the Black Bay One line. The curved cases feature a combination of finishes that elevates the watch in a contemporary fashion and offers a design language that slightly departs from the brandsiconic tool watch spirit to embrace a sophisticated, versatile, unisex chic look and feel. Fitted with Manufacture Calibers these models are at the cutting edge of technical watchmaking refinement.