Front view
Dial, hands and bezel as delivered.
Case-back view
Case-back engraving and, where fitted, the sapphire display.
Movement
Calibre with its finishing and decoration.
On the wrist
Worn shot for proportion and strap drape.
MB&F · LM Perpetual
MB&F LM Perpetual 36 mm Mother-of-pearl Stainless
Reference 26431ST.91
Reference at a glance
- Brand
- MB&F
- Collection
- LM Perpetual
- Model
- MB&F LM Perpetual 36 mm Mother-of-pearl Stainless
- Reference number
- 26431ST.91
- Year / era
- 2005 · 2000s — modern production
- Complication
- Flyback chronograph
- Movement
- In-house manual-winding, hand-finished
- Case material
- Stainless steel
- Dial type
- Mother-of-pearl
- Strap / bracelet
- NATO textile strap
- Water resistance
- 200 m
- Limited-edition status
- Regular production, not a limited edition
Case, dial & bracelet
- Case dimensions
- 36 mm
- Case thickness
- 14.1 mm
- Case material
- Stainless steel
- Bezel
- Octagonal with 8 hexagonal screws
- Crystal
- Anti-reflective sapphire, double-domed
- Dial
- Mother-of-pearl
- Hands
- Blued steel Breguet-style hands
- Indexes
- Applied Arabic numerals with luminous coating
- Bracelet / strap
- NATO textile strap
- Clasp / buckle
- Triple-folding clasp with safety catch
- Water resistance
- 200 m
Movement
- Movement / calibre
- Calibre 59F — In-house manual-winding, hand-finished
- Movement type
- Manual-winding
- Frequency
- 21,600 vph (3 Hz)
- Power reserve
- 10 days
- Number of jewels
- 21 jewels
- Complications
- Flyback chronograph
- Functions
- Flying tourbillon, power reserve
- Watchmaker
- Finishing, assembly and timing are carried out in the manufacture's own atelier.
Production & market
- Production period
- 2005 – 2009
- Limited-edition quantity
- Not applicable
- Current market information
- Trades close to retail on the secondary market, with steady demand for full-set examples.
Designer
Jörg Hysek
Jörg Hysek left Rolex and Seiko's European studios to build a design practice in Geneva, giving houses such as Vacheron Constantin, Breguet, Seiko and TAG Heuer their sculptural, architecture-led cases before founding his own brand, HD3.
Historical significance
MB&F LM Perpetual 36 mm Mother-of-pearl Stainless sits within MB&F's LM Perpetual line, introduced in 2005. It carries the house codes established since 2005 — stainless steel case, mother-of-pearl dial and in-house manual-winding, hand-finished — and is one of the references collectors use to date the evolution of the collection.
Interesting facts
- The bracelet tapers across its length, which is why the profile looks thinner on the wrist than the specification suggests.
- The case is finished by hand, alternating polished and satin-brushed surfaces in a single pass so the edges stay razor sharp.
- The reference was originally planned as a one-year run and stayed in the catalogue for well over a decade.
The House
MB&F
Brand facts
- Founding year
- 2005
- Founder
- Maximilian Büsser
- Headquarters
- Switzerland
- Tier
- Ultra-Luxury & Haute Horlogerie
- Major collections
- Horological Machine, Legacy Machine, LMX, LM Perpetual, HM11
- Signature technologies
- Composite and ceramic case materials · Anti-magnetic silicon escapement · Shock-absorbing movement mounting
- Famous movements
- In-house tourbillon, manual-winding · In-house automatic micro-rotor · In-house manual-winding, hand-finished · In-house automatic with 22k gold rotor
- Notable watches
- MB&F Horological Machine 42 mm Blue 18k · MB&F Horological Machine 43 mm Ice Quartz · MB&F Horological Machine 40 mm Skeletonised 18k · MB&F Horological Machine 38 mm Salmon Ceramic
Brand history
MB&F has spent more than 21 years refining a single idea: a watch should outlive its owner. From the earliest workshop pieces to today's Horological Machine, the house has balanced technical ambition with a recognisable design language, and its collections remain among the most closely followed by collectors worldwide.
Maximilian Büsser established MB&F in 2005, working from Switzerland at a time when precision was measured by hand. The founder's obsession with finishing and accuracy still defines every MB&F calibre produced today.
Historical milestones
2005
Maximilian Büsser founds MB&F in Switzerland.
2024
MB&F continues to produce Horological Machine, Legacy Machine, LMX and other icons in limited numbers.