Gos Caliber Gos01

GoS Caliber GoS01

Gos Caliber Gos01

Manufacturer GoS (Gustafsson & Sjögren)
Caliber Number GoS01
Base Caliber
Martin Braun (see below)
Movement Type Mechanical, manual-wind
In-House? Yes
Jewels Needs confirmed
Vibrations Per Hour 18,000 bph
72 hours
Silicon escape wheel and anchor
Anti-Shock System KIF
Features Central hours; central minutes; small running seconds at 6:00; power reserve indicator on the back
Country of Manufacture Switzerland / Sweden
Known Models GoS Winter Nights – For Purists

The  GoS Norrsken caliber GoS01 (aka GoS caliber 1) is a handwound mechanical movement found in a limited edition GoS “Winter Nights – For Purists” watch. It is the brand’s first in-house movement, and quite possible the world’s first movement made from damascus steel. It features a large 4/5 bridge, with the bridge and balance cock being constructed from the same piece of steel. This movement was introduced in 2013.

In GoS’s own words:

“The GoS movement is a collaboration between GoS and Martin Braun (of Antoine Martin/MHO) and is based on a new caliber of his. Our ambition is to show as much of the intricate damascus steel patterns as possible. With this goal in mind, we created a 4/5 bridge and balance cock made from one piece of solid handforged damascus steel. This movement combines Martin Braun’s attention to details and long experience as a movement manufacturer with the craftsmanship and esthetics of the GoS team. The caliber includes Martin Braun’s HPE innovation in the use of Silicium in the escape mechanism to not only extend the service intervals but also increase the overall effectiveness of the mechanism compared to a conventional design.” –source

Gos Caliber Gos01 Balance Wheel Glucydur Kif

Some of the topics covered in this caliber listing:

GoS x Martin Braun:

As Gos mentioned above, the development of this caliber was a partnership between GoS and Martin Braun – it is essentially based on a Martin Braun caliber. In a recent conversation, GoS provided Caliber Corner with more details about the base movement:

“It was based on an MHO caliber that Martin also used as a basis for Antoine Martin. The mainplate and internals of GoS01 is also identical to the Buben Zorweg movement BZ01-MHO except for the calendar mechanism.” -Patrick Sjögren (published with his permission)

MHO AG (aka Manufacture Horlogère Obwalden) was founded by Martin Braun in 2009. Below is a drawing of the base movement:

Gos Caliber Gos01 Bz01 Mho Base


Finishing is extremely important to GoS the concepts behind their designs. Damascus is layered, hand-forged steel and is expressed differently depending on the landscape and amount of real estate to work with. With this in mind, GoS sought to show as much of the unique patterning as possible. The large bridge design is partly why GoS went with Martin Braun’s framework.

In GoS’s own words:

“Patrick Sjögren applies his finishing to the movement parts in damascus steel with the goal to have a good balance between the raw damascus steel surface and the traditionally highgloss polished beveled edges. Finishing damascus steel is very labor intensive as every part is polished, beveled and etched multiple times to achieve the final result. The Damascus steel in the Winter Nights GoS movements is forged into the traditional woodgrain pattern, also known as the ladder pattern. This is one of the oldest known damascus steel patterns and is still considered to be one of the most beautiful and expressive patterns.” -GoS Winter Nights press-release (May 1, 2013)

Additionally, all of the wheels on the Gos01 are polished according to Geneva Seal standards, which translates to:

“The wheels of the going train must be chamfered above and below and have a polished sink. In wheels 0.15 mm thick or less, a single chamfer is allowed on the bridge side. In wheel assemblies, the pivot shanks and the faces of the pinion leaves must be polished.” –source

Gos Caliber Gos01 Gos1 Prototype

Limited Production:

The Winter Nights – For Purists watch powered by the caliber GoS01 was originally slated for a production run of 10 pieces. A total of 5 pieces were ordered and the remaining production was discontinued. The watches are still numbered out of 10, even though only 5 were actually made.

At $19,000 USD for each piece, the financing simply did not make sense for GoS. Especially considering that the time alone for manufacturing one watch was over 20 full work days – not including time and cost of producing the base movement.

Below is an image of the original prototype of the GoS01. Notice that the original pattern differs from the final production model pictured at the top of this post.

Gos Caliber Gos01 Prototype

GoS01 VS GoS02:

Following the Winter Nights – For Purists model in 2013, the brand released the Winter Nights – Unique Piece watch. This subsequent model featured a different calibre GoS02, which is based on the Technotime cal. TT718.

Additional Resources:

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