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Movement tier: unclassified · caliber Hublot Cal. HUB4700 UNICO: in-house automatic flyback chronograph, 28,800bph, 72h PR; used in Spirit of Big Bang 45; column-wheel, bi-directional rotor · 72h power reserve (3 days)
Large case: suits wrists 7 in+ (18 cm+)
45 mm case. A bold, statement-size wear. Best suited to larger wrists where the case sits flush.

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Authentication

Barrel-shaped case with Cal. HUB4700 UNICO; the 96h reserve and barrel profile distinguish it from the round Big Bang.

Known issues in the market
  • The Spirit has a barrel case; any Spirit-labeled watch in a round case has wrong case or wrong model labeling.
  • Cal. HUB4700 has 96h reserve; a Spirit caseback showing HUB1242 architecture has the wrong movement fitted.
AreaWhat to checkWhat is correctRed flag
caseBarrel case profileDistinctly barrel-shaped case; visually different from the round Big BangRound case on a Spirit-labeled watch; wrong case or model labeling
casebackCal. HUB4700 architectureHUB4700 UNICO architecture with 96h reserve bridge layout visible through casebackHUB1242 or other movement architecture; wrong movement for Spirit
caseTitanium weightVery light for case size; titanium case substantially lighter than steel equivalentHeavy for case size; non-titanium case material
Common legitimate replacements
  • Rubber strap; Hublot OEM.
  • Crown; Spirit-specific crown profile.
Expert resources: Hublot Spirit of Big Bang product documentation; Hublot authorized service.

Authentication guide

Last reviewed June 2026

The Spirit of Big Bang uses a tonneau case that is immediately distinct from the round Big Bang. Any round-cased watch presented as a Spirit is not genuine. Authentication then moves to the UNICO movement and the H-screw bezel.

Known reproduction risks

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HIGH RISK

Round Big Bang case misrepresented as a Spirit of Big Bang.

  • Round case instead of tonneau: immediately disqualifying
  • No Spirit of Big Bang has a round case from any era
HIGH RISK

Non-UNICO movement inside a correct tonneau case shell.

  • Column wheel absent through caseback
  • Rotor architecture inconsistent with HUB4700
  • Flyback function not operational

Dial variants by era

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EraDescriptionIdentifiers
2014 to presentTonneau (barrel) case with skeleton dial showing the HUB4700 UNICO flyback movement; subdials integrated into the movement architecture rather than applied discs.
  • Tonneau case outline is mandatory; the case is emphatically not round
  • Lugs curve inward from the tonneau body, creating a distinctly shaped lug gap
  • Six H-shaped bezel screws present on the tonneau bezel, same as round Big Bang

Service part flags

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Case shape

Original: Tonneau (barrel) case measuring 45mm lug-to-lug at the widest point; case height 16.5mm.

Replacement tells
  • Round case: not a Spirit of Big Bang regardless of other markings
  • Case height below 15mm suggests a non-original case
Crystal

Original: Sapphire crystal with pronounced dome following the tonneau case curvature; anti-reflective treatment on both inner surfaces.

Replacement tells
  • Flat mineral crystal instead of curved sapphire
  • Visible reflections where genuine should be near-AR-coated
  • Crystal edge not flush with the bezel all the way around the tonneau perimeter

Case back markings

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2014 to present
  • Sapphire caseback showing HUB4700 UNICO caliber
  • Column wheel visible at 9 o'clock through caseback
  • Titanium inner case ring engraved with reference and serial
  • "642.NX.0170.RX" or variant on standard titanium rubber strap model

Movement tells

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  • The HUB4700 shares the UNICO flyback architecture with the round Big Bang; the same column wheel and flyback pusher logic applies.
  • The bi-directional winding rotor is skeletonized and clearly visible through the tonneau caseback; it should spin freely in both directions.
  • Flyback function at the 4 o'clock pusher (mapped to the tonneau case geometry) resets and restarts in a single press; a non-flyback movement requires three pushers for the same sequence.
Sources: Hublot Spirit of Big Bang product page.

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