Its 44 mm-diameter white gold case, polished and satin-finished to emphasise the elegance of the entire timepiece, is fitted with a bezel adorned with 76 diamonds.

A Patented Tourbillon That Is the Only One of Its Kind

Constantly pushing back the limits of precision, the master watchmakers and engineers of the Montblanc Manufacture in Villeret have conceived the ExoTourbillon, an ultra-precise regulating organ, equipped with an original structure, that performs one revolution per minute. In this in house-developed and patented structure, the bottom of the tourbillon cage, smaller than that of the screw balance, carries the escape-wheel, the pallets and the balance-spring stud that is attached to the balance-staff collet at both ends of the cage. This innovative cage driven by the movement's gear-train turns without friction in in a two-point bearing at the foot of its staff. Pierced at its center, it allows the passage of the extremely long balance-staff, the pivots of which rotate against jewels. This unique structure allows the balance, as it oscillates outside the cage and on a higher plane, to remain isolated from the cage. Due to its reduced size and the fact that it is freed from the weight of the balance, the cage requires 30% less energy than a conventional tourbillon to drive its rotational movement.

A further advantage of this innovative construction (the name of which derives from the Greek prefix “Exo”, meaning “outside” or “external”) is also found in terms of precision, since the balance, now isolated from the rotating cage, is not disturbed by its inertia. In order to benefit from the increased precision of this patented ExoTourbillon, Montblanc has incorporated into its movement a stop-second function obtained by inserting a small spring that is directly halting the screw balance, now freed from its cage allowing to precisely set the time without the tourbillon continuing to turn.

In order to precisely adjust the time, the tourbillon cage integrates a red marker in form of an arrow, which allows to read the seconds on the respective scale printed on the opening of the dial around the tourbillon.

A Manufacture Calibre

This innovative Tourbillon construction is integrated in Montblanc’s own in-house developed chronograph calibre that combines all the elements of a traditional chronograph with a contemporary highly performant construction: monopusher with column wheel, efficient and precise vertical coupling, automatic winding and two barrels. Two semicircular counters with hands of different lengths to match the appropriate sectorial scales, enable the Heritage Chronométrie ExoTourbillon Minute Chronograph Diamonds to tally elapsed seconds and minutes. The date, always an extremely practical indication, is soberly displayed in the centre of the dial by a dedicated hand pointing to a circular scale arranged around the blue “flinqué” guilloché circle.

The hour hand is set to advance in hourly steps, a highly practical feature in that it allows for fast and easy setting when travelling. The setting of the hour-hand has no effect on the minute- and second-hands, thus ensuring that precise time is always preserved. To set the date display, the user advances or retreats the hour-hand through 24 hours. Whenever this hand’s tip passes the 24th hour, the hand of the date display either advances or retreats accordingly.

An Exceptional Dial and Case

The sophisticated dial of the Heritage Chronométrie ExoTourbillon Minute Chronograph Vasco da Gama Diamonds with different levels and refined finishes reflects the two complications of the timepiece. The eye is first caught by the oscillations of the balance-wheel, which, as it performs each revolution every minute, arouses our curiosity about the functioning of this mysterious tourbillon. It is surrounded by a slice of aventurine, dyed dark blue of which attracts the eye, and numerous small dots evoke a starry night-sky, in reference to the sky of the southern hemisphere that guided Vasco da Gama during his voyage. Amid this star-spangled firmament, a diamond with a patented cut in the shape of the Montblanc emblem shines with all its brilliance at 12 o'clock. In the centre of the dial, the display with the date hand is adorned with a blue “flinqué” guilloché wave pattern, referring to the nocturlabium (star clock), which was one of the navigational instruments aboard the São Gabriel.

This timepiece is naturally affiliated with Vasco da Gama's floating flagship, the São Gabriel. The pane of sapphire crystal inset into the back of the case is adorned with a sketch of this historic sailing vessel, together with the signature of the intrepid explorer and seafarer. The series is strictly limited to 25 pieces, referring to the geographical latitude of 25° N, the northern-most visibility point of the Southern Cross constellation.