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In-house manufacture caliber · caliber Moritz Grossmann Caliber 100.1 (manual-wind, 42-hour power reserve, Grossmann regulator) · 42h power reserve
Medium-large: suits wrists 6.5 in+ (16.5 cm+)
41 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

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Authentication

The Benu Pure three-quarter plate chamfers must be hand-polished; machine-finished chamfers do not meet the Moritz Grossmann stated standard.

Known issues in the market
  • The Grossmann regulator spring is visible under magnification; it is a house signature distinct from a standard index regulator.
  • The three-quarter plate is the Glashütte finishing reference.
AreaWhat to checkWhat is correctRed flag
movementThree-quarter plate hand-polished chamfersSharp hand-polished chamfers on three-quarter plate bridges; consistent with Grossmann standardMachine-finished chamfers; does not meet Moritz Grossmann stated standard
movementGrossmann regulator springGrossmann regulator spring visible under magnification; distinct from standard index regulatorStandard index regulator replacing Grossmann regulator spring; non-genuine movement
casebackCal. 100.1 architectureCal. 100.1 three-quarter plate visible through caseback; manual-windNon-Cal-100.1 architecture; movement swap
Common legitimate replacements
  • Crown; Grossmann-signed only.
  • Crystal; sapphire standard.
Expert resources: Moritz Grossmann authorized service; Glashütte regional watchmaker network.

Authentication guide

Last reviewed June 2026

The Benu Pure shares the Cal. 100.1 architecture with the Atum but uses a different case geometry and dial layout. Both watches share the Grossmann eccentric-screw balance wheel as the primary authentication anchor. The Benu is slimmer at 10mm height.

Known reproduction risks

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MEDIUM

Configuration misrepresentation: Atum sold as Benu, or standard Benu sold as a limited-color variant.

  • Caseback caliber designation showing 100.0 in a Benu housing
  • Dial color not matching stated variant
  • Case dimensions exceeding 10mm height (Benu is slimmer than Atum)

Fakes are not a documented issue. Variant misrepresentation is the practical risk at this price.

Dial variants by era

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EraDescriptionIdentifiers
2019 to presentWhite or blue lacquer dial. Applied baton indices. Small seconds at 6. No date. Slim 10mm case height makes this one of the more elegant manual-winds in the Glashütte independent tier.
  • "MORITZ GROSSMANN" at 12, "GLASHÜTTE I/SA" below
  • Applied indices, typically in rhodium on white or gold on blue
  • Small seconds sub-dial at 6 with fine inner track
  • 41mm steel case at 10mm height
  • Sapphire caseback showing three-quarter plate and Grossmann balance

Service part flags

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Balance wheel

Original: Same eccentric-screw regulation as the Atum. Rim of the balance wheel has visible screws for rate adjustment. No swan-neck spring. Cal. 100.1 is the Benu-specific variant.

Replacement tells
  • Swan-neck or index regulation spring present instead of eccentric screws
  • Cal. 100.0 movement (Atum caliber) in a Benu case
  • Three-quarter plate with wrong bridge geometry for Benu

Case back markings

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2019 to present
  • Reference MG-005401 or variant
  • "MORITZ GROSSMANN" and Glashütte address
  • Caliber 100.1 designation
  • Serial number

Movement tells

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  • Cal. 100.1 power reserve is 42 hours. Same service indicators as Atum: below 36 hours is a red flag.
  • Manual crown action should be positive and smooth. Any grittiness suggests dirty pivot oil or a worn click spring.
  • Finishing should match or exceed Atum: three-quarter plate with Glashütte stripes, blued screws, hand-beveled edges.
Sources: Moritz Grossmann Benu technical documentation.

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