Apart from holding the record of 91 synthetic rubies at A. Lange & Söhne, the ZEITWERK MINUTE REPEATER also features two sapphires in its movement. While having similar technical properties as a ruby, a sapphire is clear instead of ruby red. Depending on the model, the sapphire replaces the ruby not only for technical reasons, but also for aesthetic reasons, as on the dial of the ZEITWERK family or on the zero-reset lever of the second hand of the 1815 TOURBILLON. Unlike a dark red ruby, the watchmaker can easily see through the sapphire onto the parts underneath. In some cases, like for the ZEITWERK, this is even necessary for the assembly and revision. It is also thanks to the sapphire-crystal caseback of our timepieces through which the beauty of the movement can be admired. #alangesoehne #zeitwerk #zeitwerkminuterepeater #langestoryettes #finewatchmaking