MB&F launches the LM Perpetual Chromatic series in 2026, three ultra-limited editions that dress the award-winning Legacy Machine Perpetual in baguette-cut rubies and sapphires, each limited to just 8 pieces worldwide.
A Rare Appointment With Colour
Since 2015, the LM Perpetual has earned its place as one of the most significant perpetual calendar watches in contemporary watchmaking. Now, in 2026, MB&F revisits that landmark creation with a burst of chromatic confidence. Three editions arrive: two in 18k white gold with bezels set in blue sapphires or purple sapphires, and a third in 18k red gold adorned with Mozambican rubies. Each run covers exactly 8 pieces, making these among the rarest LM Perpetuals ever produced.
The Dial: A Stage for the Complication
The LM Perpetual uses no traditional dial plate in the conventional sense. Instead, the open architecture of the movement becomes the dial itself, placing the full perpetual calendar complication in direct view from above. Skeletonised subdials rest on hidden studs, creating the visual illusion of floating indicators with no visible support. This approach is technically impossible with traditional perpetual calendar mechanisms, precisely because the grand levier (big lever) would physically block any stud-mounted subdial from functioning.
The layout follows a clockwise arc: hours and minutes at 12 o’clock, framed under the suspended balance; day of the week at 3; power reserve at 4; month at 6; retrograde leap year at 7; and date at 9. PVD-treated hands match the character of each edition: purple for the purple sapphire version, blue for the blue sapphire version, and 5N PVD gold tone for the ruby edition, echoing the warmth of the red gold case. La Montre Hermès SA handles dial production, ensuring the execution matches the ambition.
The Movement: Stephen McDonnell’s Mechanical Processor
The engine inside all three Chromatic editions is the fully integrated 581-component calibre developed by independent Northern Irish watchmaker Stephen McDonnell, produced in a single, purpose-built architecture with no module and no base movement. This point deserves emphasis: virtually every traditional perpetual calendar is a module bolted to an existing movement. The LM Perpetual is built entirely from scratch to serve one purpose.
The breakthrough lies in what MB&F calls the mechanical processor. Traditional perpetual calendars assume a 31-day default and fast-forward through redundant dates at month end, creating the notorious risks of skipped dates, jammed gears, and damaged mechanisms during adjustment. McDonnell inverted this logic: the processor defaults to a 28-day month and adds extra days as required by each individual month. The result is that every month carries exactly the right number of days, with zero fast-forwarding and zero skipping.
Additionally, the quickset pushers deactivate automatically during date changeover via an inbuilt safety mechanism, removing the primary cause of damage in conventional systems. A dedicated pusher allows direct year adjustment without scrolling through up to 47 months, as traditional perpetual calendars require. The calibre beats at 18,000 bph (2.5 Hz) via a bespoke 14 mm balance wheel with traditional regulating screws, and the double mainspring barrels deliver a 72-hour power reserve.
The finishing throughout follows 19th-century standards: polished bevels, Geneva waves, internal bevel angles highlighting hand craftsmanship, and hand-made engravings executed by specialist Glypto. At the back, through the display caseback, the escapement animates the view, but it is the superlative finishing of bridges and plates by teams including C-L Rochat, MBG WATCH DÉCOR, DSMI, and 2B8 that commands the real attention. That suspended balance connects to the escapement on the reverse of the movement via what is likely the world’s longest balance staff, piercing the full depth of the movement.
The Case and Gem Setting
The case measures 44 mm in diameter and 17.5 mm in height, housing 69 components, with sapphire crystals on both top and display back treated with anti-reflective coating on both faces. Water resistance reaches 30 metres. Case decoration comes from Termin’hor, and Cheval Frères produces the crown and correctors.
The defining feature of the Chromatic editions is the bezel, where 48 baguette-cut gemstones trace an unbroken coloured ring around the case. Baguette setting is one of the most demanding stone-setting disciplines in fine jewellery and watchmaking. Each rectangular stone needs precise individual adjustment: the facets must align perfectly flush with neighbouring stones, the metal separating each stone requires exact filing to match the stone’s specific dimensions, and any deviation in depth or angle causes light to break irregularly across the row. STG Création SA in Geneva handles this process entirely by hand for MB&F, and the result is a perfectly even channel of colour around the bezel without any increase in case diameter. The red ruby edition uses 1.95 carats of Mozambican rubies; the blue sapphire edition draws 1.95 carats from Madagascar and Sri Lanka; the purple sapphire edition carries 1.93 carats of Madagascar stones.
A Chromatic Triumph
The LM Perpetual Chromatic editions represent exactly the kind of project that defines MB&F‘s approach: technically uncompromising and visually bold, with each discipline, gemstones, movement finishing, and open-dial architecture, reinforcing the others rather than competing for attention. The LM Perpetual won the GPHG Best Calendar Watch prize in 2016, and the architecture behind these new pieces remains unchanged in its fundamental brilliance. The official retail price has been confirmed at the time of publication: CHF 228,000 + VAT (US$ 312,000 / EUR 248,000 + tax). Expect them to disappear before most collectors even confirm their interest.
MB&F LM Perpetual Chromatic Editions Technical Specifications
Legacy Machine Perpetual has been crafted in the following editions:
- in platinum 950 with blue face (limited to 25 pieces);
- in 18k red gold with grey face (limited to 25 pieces);
- in 18k white gold with purple face (limited to 25 pieces);
- in 18k white gold with dark grey face;
- in grade 5 titanium with green face (limited to 50 pieces);
- in 18k yellow gold with blue face (limited to 25 pieces);
- in palladium 950 with aquamarine face (limited to 25 pieces);
- in stainless steel with salmon face;
- in stainless steel with diamond-set bezel (exclusive to Ahmed Seddiqi – 5 pieces);
- in 18k rhodium-plated red gold with red rubies bezel (limited to 8 pieces);
- in 18k rhodium-plated white gold with blue sapphires bezel (limited to 8 pieces);
- in 18k rhodium-plated white gold with purple sapphires bezel (limited to 8 pieces).
Engine
Fully integrated perpetual calendar developed for MB&F by Stephen McDonnell, featuring dial-side complication and mechanical processor system architecture with inbuilt safety mechanism. Manual winding with double mainspring barrels. Bespoke 14 mm balance wheel with traditional regulating screws visible on top of the movement. Superlative hand finishing throughout respecting 19th century style; internal bevel angles highlighting hand craft; polished bevels; Geneva waves; hand-made engravings.
- Power reserve: 72 hours
- Balance frequency: 18,000bph / 2.5Hz
- Number of components: 581
- Number of jewels: 41
Functions/indications
- Hours, minutes, day, date, month, retrograde leap year and power reserve indicators
Case
- Material: 18k 5N+ red gold, 18k white gold, 18k 3N yellow gold, platinum 950, grade 5 titanium, palladium 950 or stainless steel.
- Dimensions: 44 mm x 17.5 mm
- Number of components: 69 components
- Water resistance: 30 m / 90′ / 3 ATM
Gemstones (for LM Perpetual Chromatic editions)
- Red rubies: 1.95 cts (Mozambique)
- Blue sapphires: 1.95 cts (Madagascar & Sri Lanka)
- Purple sapphires: 1.93 cts (Madagascar)
Sapphire crystals
- Sapphire crystals on top and display back treated with anti-reflective coating on both faces.
Strap & buckle
- Black, grey, brown, blue or white hand-stitched alligator strap with gold / platinum / titanium or stainless-steel folding buckle matching case material.
