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Credor

Spring Drive Tourbillon

Ref. GBRT999
2007–present · 40mm · caliber Seiko Cal. 7R08: Spring Drive with flying tourbillon, manual-wind; tri-synchro regulator + rotating escapement carriage; platinum case; one of the rarest Seiko movements ever produced
Mass-produced

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Movement tier: unclassified · caliber Seiko Cal. 7R08: Spring Drive with flying tourbillon, manual-wind; tri-synchro regulator + rotating escapement carriage; platinum case; one of the rarest Seiko movements ever produced
Medium-large: suits wrists 6.5 in+ (16.5 cm+)
40 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

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Authentication

The Credor Spring Drive Tourbillon combines Spring Drive tri-synchro regulation with a flying tourbillon in a platinum case. Production is extremely limited and the watch is primarily known in Japan. The same authentication logic as the Eichi II applies: misrepresentation rather than counterfeiting is the risk.

Known issues in the market
  • Both the glide seconds hand and the tourbillon rotation should be observed; the glide motion is the Spring Drive tell and should be present regardless of the tourbillon.
  • Platinum case should carry correct Japanese and international precious metal marks; platinum weight is significantly heavier than white gold of the same dimensions.
  • Production is so limited that any example should have documented provenance and ideally a Seiko/Credor service record.
AreaWhat to checkWhat is correctRed flag
movementSpring Drive glide seconds combined with tourbillon rotationTourbillon rotates once per minute with smooth, consistent motion; seconds display shows glide motion; both mechanical systems should be operational simultaneouslyEither the tourbillon stopped or the seconds display showing tick motion; tourbillon cage rotation other than one per minute
casePlatinum case weight and hallmarksPlatinum is approximately 40% heavier than white gold for the same dimensions; correct precious metal marks (Pt950 or equivalent) present on case; case weight consistent with declared materialCase weight lighter than expected for platinum; missing or incorrect metal marks; case feels like white gold rather than platinum
dialTourbillon aperture and dial finishingTourbillon aperture has clean, polished edges; any dial decoration meets Credor standards with the same depth and quality as the Eichi IIRough aperture edges; dial decoration quality inconsistent with Credor standards
movementZaratsu-polished movement visible surfacesMovement surfaces visible through the caseback show mirror-flat Zaratsu polish; no micro-scratches on polished zonesMicro-scratches or orange-peel texture on what should be Zaratsu-polished surfaces
Common legitimate replacements
  • No standard replacement parts available outside the Seiko factory service network.
Expert resources: Seiko/Credor authorized service centers in Japan are the only entities with full service capability for this movement. Contact a Credor boutique for serial number verification. For pre-owned acquisition, insist on a full service inspection at a Seiko authorized center before purchase.

Authentication guide

Last reviewed June 2026

Cal. 7R08 in a platinum case. The Spring Drive glide spring is the definitive authentication test: a genuine Spring Drive runs silently with a continuous sweep. Any audible tick is disqualifying.

Known reproduction risks

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HIGH RISK

Non-Spring Drive movement in Credor case or alternative tourbillon

  • Audible ticking or stepping seconds hand is definitive: not a Spring Drive
  • Conventional lever escapement visible through caseback or dial
  • Tourbillon cage design differs from Cal. 7R08 architecture

The silent sweep test is immediate and requires no tools. A claimed Spring Drive that ticks is not a Spring Drive.

Dial variants by era

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EraDescriptionIdentifiers
Spring Drive Tourbillon productionSkeletonized or partially skeletonized dial revealing the tourbillon carriage and Spring Drive mechanism. Platinum case.
  • Tourbillon carriage visible through dial aperture
  • Tri-synchro regulator (glide spring visible, no conventional pallet fork)
  • Platinum case markings (Pt950 or equivalent)

Service part flags

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Movement (Cal. 7R08)

Original: Tri-synchro regulator with glide spring. Tourbillon at 6 o'clock. No audible tick.

Replacement tells
  • Any audible ticking sound from the movement
  • Conventional pallet fork and lever visible rather than the glide spring
  • Tourbillon cage absent or at a different position

Case back markings

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All production
  • Credor and Seiko markings
  • Cal. 7R08 designation
  • Pt950 platinum purity mark
  • Serial number

Movement tells

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  • Spring Drive runs silently with a continuous gliding sweep of the seconds hand. No tick. No stepping.
  • The glide spring (tri-synchro regulator) controls rate electromagnetically; it requires no conventional lever or detent.
  • Wind the crown and observe the power reserve. The Spring Drive power reserve on this caliber is approximately 72 hours.
  • The tourbillon carriage should rotate at one revolution per minute (visible through the dial aperture).
Sources: Credor official.

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