Timed to coincide with the 60th anniversary of the firm’s original diver’s watch, Blancpain’s Fifty Fathoms Bathyscaphe can dive to new depths: It is water resistant to 300 feet. New developments in the self-winding mechanical timepiece (from $10,500 for men and $9,500 for women) include a nonmagnetic silicon balance spring, which is protected by a sapphire-crystal caseback and provides corrosion resistance and durability; it is thus able to maintain more accurate measurements over time. The company also emplo…