In 15 years at MB&F, only one watch has ever been crafted from yellow gold and that was the LM101 Frost Yellow Gold until now. Today, five years later, the Legacy Machine Perpetual makes its appearance in Yellow Gold. First launched in 2015, the LM Perpetual series is one of MB&F’s best sellers with limited editions in white gold, red gold, platinum, and titanium. The vast majority of these variations are sold out; therefore, it was time to introduce a new 18k yellow gold case with a deep blue face, limited to just 25 pieces just like the rest of the previous iterations that were available with the same limitation with the exception of the titanium one which was available in a limited edition of 50 pieces.

LM Perpetual features a fully integrated 581-component calibre —no module, no base movement— with a revolutionary new system for calculating the number of days in each month. And it holistically reinterprets the aesthetics of the perpetual calendar by placing the full complication on a dial-free display underneath a spectacular suspended balance.

The perpetual calendar is one of the great traditional complications, calculating the apparently random complexity of the varying numbers of days in each month − including the 29 days in February during leap years. But traditional perpetual calendars do have a few drawbacks: dates can skip; they are relatively easy to damage if adjusted while the date is changing, and the complications are usually compromises of modules powered by base movements.

The fully integrated, purpose-built movement of Legacy Machine Perpetual has been designed from scratch for trouble-free use: no more skipping dates or jamming gears, and the adjuster pushers automatically deactivate when the calendar changes, so no problems there either. Traditional perpetual calendar mechanisms use a 31-day month as the default and basically "delete" superfluous dates for the months with fewer days —by fast-forwarding through the redundant dates during the changeover. A traditional perpetual calendar changing from February 28 to March 1 scrolls quickly through the 29th, 30th and 31st to arrive at the 1st.

LM Perpetual turns the traditional perpetual calendar system on its head by using a “mechanical processor” instead of the conventional space-consuming grand levier (big lever) system architecture. The mechanical processor utilizes a default 28-day month and adds extra days as required. This means that each month always has the exact number of days required; there are no fast-forwarding or skipping redundant days. And while the leap year can only be set on traditional perpetual calendars by scrolling through up to 47 months, LM Perpetual has a dedicated quickset pusher to adjust the year.

With its open dial revealing the full complication and suspended balance, it's the harmonious mechanical beauty of LM Perpetual that really steals the show. And in an interesting technical twist, that eye-catching balance hovering on high is connected to the escapement on the back of the movement by what is likely to be the world's longest balance staff.

Using an innovative system developed especially for Legacy Machine Perpetual, the subdials appear to "float" above the movement with no visible attachments. The skeletonized subdials rest on hidden studs, which is technically impossible with traditional perpetual calendar mechanisms because they would block the movement of the grand levier. Taking a clockwise tour of the dial, at 12 o'clock we see the hours and minutes nestled between the elegant arches of the balance; day of the week at 3 o'clock, power reserve indicator at 4 o'clock, a month indicator at 6 o'clock, retrograde leap year indicator at 7 o'clock, and date at 9 o'clock.

The Legacy Machine Perpetual won the Best Calendar Watch Prize at the GPHG —Grand Prix d’Horlogerie de Genève— in 2016. The new MB&F Legacy Machine Perpetual Yellow Gold is available in a limited edition of 25 pieces.

Sticker Price $167,000 USD. For more info on MB&F click here.