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Mass-produced#2 in familyOfficial press photos

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In-house manufacture caliber · caliber Elite 670 SK (automatic, skeleton, open-worked)
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

Zenith star motif in the skeletonized bridges is structural in genuine examples and decorative only in fakes.

Known issues in the market
  • The star motif is load-bearing in the original Elite 670 SK; purely decorative in counterfeits.
  • Open-worked bridges must visually integrate case and movement architecture.
AreaWhat to checkWhat is correctRed flag
movementStar motif in skeletonized bridgesZenith star motif present in skeletonized bridges as structural element; visible through dial and from casebackStar motif absent; generic openwork pattern without star; star present as applied ornament rather than structural cutout
dialSkeleton dial integrationDial and movement visually integrated; movement architecture readable through open sectionsSolid dial sections blocking movement view; non-skeleton movement installed in skeleton case
casebackCal. Elite 670 SK identityCal. Elite 670 SK designation; skeleton rotor; Zenith in-house architectureNon-Zenith caliber; solid-plate movement in skeleton case; incorrect caliber engraving
Common legitimate replacements
  • Original Defy Classic rubber or leather strap; factory options through Zenith.
Expert resources: Zenith Defy Classic 10.9000.670 press materials. Zenith Cal. Elite 670 SK documentation.

Authentication guide

Last reviewed June 2026

The Defy Classic uses the skeletonized Elite 670 SK caliber in the octagonal Defy case. The open-worked movement is the primary visual statement. Authentication focuses on movement finishing quality and the octagonal case geometry.

Known reproduction risks

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LOW

The Defy Classic has low replica exposure. The main risk is amateur dial or movement swaps in pre-owned examples.

  • Bridge finishing with rough edges or uneven bevel quality
  • Octagonal bezel with rounded face transitions rather than sharp right-angle edges
  • Movement with bridge layout inconsistent with the Elite 670 SK

Dial variants by era

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EraDescriptionIdentifiers
2017 to presentOpen-worked dial with the skeletonized movement visible through the dial plate. The octagonal Defy case with alternating polished and brushed surfaces. Available in silver and steel variants.
  • Open-worked dial with the Elite 670 SK movement visible through the sapphire dial cover
  • Octagonal bezel with eight sides in alternating polished and brushed surfaces
  • "ZENITH" text and star logo visible on the movement plate or on a dial bridge
  • Date window integrated into the skeletonized dial architecture at 4 to 5 o'clock position
  • No conventional dial surface -- the movement bridges are the visual element
  • "Defy" text on the movement plate or case

Service part flags

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Octagonal bezel

Original: Eight-sided bezel with alternating polished and brushed faces. Each face transition should be a precise right-angle edge with no rounding. The bezel is fixed -- no rotation on the Defy Classic.

Replacement tells
  • Bezel face transitions that are rounded or softened rather than precise right-angle edges
  • Surface finish inconsistency between alternating faces under the same light angle
  • Bezel that rotates -- the Defy Classic has no bezel rotation
Skeletonized movement finishing

Original: The Elite 670 SK bridges are beveled, polished on the edges, and brushed on the flat surfaces. The skeletonization cuts should be smooth with no burring. The balance wheel and escapement should be visible and clearly finished.

Replacement tells
  • Bridge edges that are not beveled or that show uneven polishing depth
  • Skeletonization cuts with visible rough edges or tool marks under loupe
  • Movement finishing inconsistent between bridges on the same movement -- genuine Zenith Elite finishing is consistent across all bridges

Case back markings

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2017 to present
  • Exhibition caseback (or case design may show movement from front and back)
  • "Zenith" and "Defy Classic" identification
  • Reference 10.9000.670 on the case band
  • "Swiss Made" on the movement plate or caseback
  • Cal. Elite 670 SK designation
  • Serial number on case band

Movement tells

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  • Cal. Elite 670 SK beats at 28,800bph with the power reserve typical of the Elite family. The balance wheel should oscillate with a stable, regular amplitude visible through the open movement.
  • The skeletonized caliber is visually exposed. Any lubricant degradation shows as sluggish balance amplitude or a balance that stops when the watch is inverted. Check amplitude in multiple positions.
  • Defy Classic service requires authorized Zenith service due to the finishing standards required on re-assembly of a skeletonized caliber.
Sources: Zenith -- Defy Classic and Elite 670 SK specification; WatchUSeek -- Zenith Defy forum.

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