Calibre 97 With the Calibre 97, (originally introduced in 1997 at the World Presentation of Haute Horlogerie), Franck Muller is the first watch brand to have perfected the bell chime in a wristwatch; a world premiere in the history of watchmaking. Preceding the production of this watch, the sound quality now heard in the Grande and Petite Sonnerie was only possible in a pocket watch. Originally, 18th century watchmakers created this technique in very full shapes so as to leave the maximum amplitude for the sound, which escaped through elaborate designs in the open casework. Franck Muller was able to successfully reproduce the sound in a wristwatch as a result of extensive research on complicated alloys and the realization that the bell?s outlines must fit into a case, the diameter and height not to exceed 36.80mm and 11.3mm respectively. There are two hammers which strike the inside of the bell, producing a high and low sound, fromwhich one can distinguish the hours, quarters andminutes. The Grand Sonnerie, with a ?passing-chime? announces the hours and quarters on the quarter and the Petite Sonnerie sounds the hours and quarters at the appropriate time. There is also a silence mechanism should the user not wish to hear the chimes. In addition, the Calibre 97 also has aminute ? repeater which offers the possibility of hearing the hours, quarters and minutes upon request. On the dial, the user can see the renowned strikingmechanismindicator patented by Franck Muller as well as a ?silent mode?, ?Petite Sonnerie? and ?Grande Sonnerie? indicator. The Calibre 97 also incorporated a third complication, the perpetual calendar where the day of the week, date, month and retrograde monthly equation of time , the 24 hour counter , leap-years and moon phases are all visible on the dial. This wristwatch is a unique piece in solid 950 platinum set with 48 baguette diamonds on the scope, 50 brilliant-cut diamonds on the lateral side of the scope, 46 baguette diamonds on the horns and a brilliant-cut diamond in the crown.