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Armin Strom Gravity Equal Force Ultimate Sapphire Limited Edition

Introduced in 2019, the Armin Strom Gravity Equal Force is the world’s first automatic watch with constant force transmission, which results in consistent power delivery to the balance.

Now the Swiss luxury watch manufacture presents the Gravity Equal Force Ultimate Sapphire, a strikingly cool monochrome version with an off-center grey-toned sapphire dial with an extraordinary view of the exquisitely-finished manufacture movement.

Its self-winding ASB19 caliber offers a power reserve of 72 hours. The movement’s black plate guilloche pattern was created by hand by the celebrated Finnish watchmaker Kari Voutilainen.

The off-center grey-toned sapphire dial offers an unobstructed view of the fascinating mechanics inside the case and emphasizes the brand’s passion for transparent mechanics, which are at the core of its design philosophy.

The bridges are coated with dark grey ruthenium; the barrel and the micro rotor are coated with rhodium.


The Gravity Equal Force’s ASB19 movement includes a “stop work” mechanism that prevents the mainspring from fully unwinding, thus leveraging only the part of the mainspring’s unwinding process that can deliver power most consistently.

The steel hands with Super-LumiNova® filling are manufactured by Armin Strom and like all of the visible parts of the movement, are meticulously hand-finished in-house.

Presented in a classic 41 mm stainless-steel case, the Armin Strom Gravity Equal Force Ultimate Sapphire comes with a black fabric strap with light grey-stitching, subtly maintaining the watch’s resolutely cool monochrome color scheme.

This horological marvel was designed and produced in-house at the brand’s manufacture in Biel. Like every Armin Strom watch, its movement has been assembled twice. After its first assembly, the movement was painstakingly disassembled and each individual part was cleaned, dried, reassembled and lubricated before being meticulously regulated, tested, and returned to the case.

The Gravity Equal Force Ultimate Sapphire will be available from October 2021 in a limited quantity of 15 pieces for 2021. Due to the limited production capacity, the special timepiece will be available subsequently in a very small number of pieces per year.

Technical details

Model: Armin Strom Gravity Equal Force Ultimate Sapphire
Ref. AS/ID ST21-GEF.SA.VE.M.30

Armin Strom manufacture Caliber ASB19
Automatic winding with micro rotor, Geneva-drive equal force barrel, offset display with subdial seconds
Regulating system: Balance wheel with 4 regulating screws
Power reserve: Geneva stop-work limited to 72 hours
Dimensions: 35.52 mm x 11.67 mm
Frequency: 3.5 Hz (25,200 vph)
Finishing: Hand-finishing to the highest quality level
Jewels: 28
Number of components: 202

Hours, minutes, seconds, power reserve indicator

Stainless steel
Sapphire crystal and case back with anti-reflective treatment
Diameter: 41 mm
Height: 12.65 mm
Water resistance: 3ATM

Grey toned off-center sapphire dial with subdial
Hands: Manufactured by Armin Strom, steel with hand finishing and Super-LumiNova® filling

Delivered with a black fabric strap with light grey-stitching and stainless-steel double folding clasp

CHF 22,900 / EUR 20,000 / USD 22’900

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