Armin Strom presentS the new Gravity Equal Force Ultimate Sapphire Rose Gold, a special edition distinguished by dial transparencies. Price: CHF39,400
Independent Swiss watch brand Armin Strom has presented the new Gravity Equal Force Ultimate Sapphire Rose Gold, a special edition distinguished by its warm tones and dial transparencies.
Originally launched in 2019, the Gravity Equal Force was the first automatic watch to feature a patented equal-force transmission integrated into the mainspring barrel (read our review here). Since then, it has been released in various iterations.
In 2021, the first Gravity Equal Force Ultimate Sapphire edition introduced a sapphire crystal dial, revealing even more of the movement’s sophisticated movement architecture.
The new version, produced in limited runs of just 20 pieces per year, houses Armin Strom’s sculptural Calibre ASB19 in a full 18K rose gold case, which contrasts gently with a brown guilloché mainplate and rose gold-coloured bridges.
As is customary at Armin Strom, all components are meticulously hand-finished, whether visible or not.
The three bridges are bevelled and straight-grained by hand, while the mainplate is decorated with a grain d’orge guilloché pattern, precisely cut using a traditional hand-operated guilloché machine in the atelier of acclaimed independent watchmaker Kari Voutilainen.
Crafted from transparent sapphire crystal, the off-centre dial appears to float above the movement. It is fitted with facetted and polished rhodium-plated hour and minute hands, produced in-house and filled with Super-LumiNova for enhanced legibility in low-light conditions.
A small seconds sub-dial is positioned between 7 and 8 o’clock.
The three bridges, which occupy the right-hand portion of the open display, support a unidirectional micro rotor at the top and an innovative barrel at the bottom.
This barrel incorporates a mechanism designed to deliver consistent torque to the balance, hence the model’s name, and to improve rate stability. It serves a similar function to complications such as the fusée-and-chain transmission or the constant-force escapement, but achieves this through a different approach.
Inside the mainspring barrel, a stop-works declutch system limits the torque delivered to the balance, distributing power more smoothly. Thanks to a Geneva wheel (also known as a Maltese cross) mounted on the barrel housing cover, the barrel’s rotation is limited to just nine full turns out of a possible 12.5. This corresponds to the flattest and most consistent 72% of the mainspring’s torque curve. As the barrel housing unwinds around the arbor, a pin counts the rotations on the Geneva wheel until it reaches the locked position and halts further unwinding.
On the caseback, the central inscription notes that the hand-wound Calibre ASB19 was designed and manufactured in-house by Armin Strom, adjusted in all positions, and fitted with 28 jewels. The balance beats at a frequency of 3.5 Hz (25,200 vibrations per hour) and offers a power reserve of 72 hours.
Black-polished screws and decorative techniques such as perlage, Geneva stripes, and circular brushing can be observed throughout the movement. These are not mere ornamentation, but an integral part of the calibre’s visual identity.
Measuring 41 mm in diameter and 12.65 mm thick, the rose gold case combines satin-brushed and polished finishes and is water-resistant to 30 metres / 100 feet. It is paired with a brown nubuck strap in a matching hue.
The price of the Armin Strom Gravity Equal Force Ultimate Sapphire Rose Gold, ref. RG24-GEF.SA, is CHF 39,400. arminstrom.com
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