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Movement tier: unclassified · caliber Customised ETA 7001 + ROCS 4 module (oil-filled chamber, integrated solar cell for e-Crown functionality)
Large case: suits wrists 7 in+ (18 cm+)
44 mm case. A bold, statement-size wear. Best suited to larger wrists where the case sits flush.
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Both the oil system and the solar-powered e-Crown must function; either failure requires Ressence service and affects the watch materially.
Known issues in the market
The solar cell beneath the dial charges the e-Crown; a watch stored in darkness may need light exposure before the e-Crown responds.
Oil condition should be inspected as on Type 3.
Area
What to check
What is correct
Red flag
dial
Oil-filled chamber clarity
Clear, bubble-free oil across the dial chamber
Cloudy, yellowed, or bubbled oil; seal degradation
movement
e-Crown response after light exposure
e-Crown responds and sets time after adequate light exposure
Non-responsive e-Crown after light exposure; module failure
dial
Solar cell function through the dial
Solar cell charges e-Crown under ambient light
e-Crown does not charge; solar cell failure
caseback
Ressence serial and reference
Serial and reference correctly engraved
Missing or incorrect engravings; non-genuine caseback
Common legitimate replacements
Oil system; Ressence authorized service only.
e-Crown module; Ressence authorized service only.
Expert resources: Ressence authorized service only; ressencewatches.com Type 4 documentation.
Authentication guide
Last reviewed June 2026
The Type 4 adds a solar-powered e-Crown function to the oil-fill ROCS display. A solar cell integrated beneath the sapphire dome harvests light to charge the e-Crown electronic module. 44mm titanium case. The solar cell is visible as a dark ring within the oil-filled display.
Known reproduction risks
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LOW
No known replica. The combination of oil-fill ROCS display, integrated solar cell, and e-Crown module is unique to Ressence Type 4 and impossible to replicate.
Absence of the solar cell peripheral ring within the oil display disqualifies a claimed Type 4
Presence of a physical crown on the case indicates a different Type variant or modification
Verify three things before purchase: oil clarity and depth, solar cell visibility within the display, and e-Crown function after light exposure.
Dial variants by era
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Era
Description
Identifiers
2016 to present
Oil-filled display with an integrated solar cell (visible as a peripheral dark ring beneath the sapphire) and the e-Crown module on the caseback. Black or grey dial. 44mm titanium case without a physical crown.
Solar cell visible as a peripheral dark ring within the oil-filled display
No physical crown on the case
e-Crown module on caseback (same architecture as Type 2)
Oil-filled display with liquid depth (same as Type 3)
Type 4 designation on caseback
44mm titanium case
Service part flags
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Solar cell
Original: The solar cell is a peripheral ring integrated beneath the sapphire crystal and visible within the oil-filled chamber. It should be consistently dark (photovoltaic material) without any surface damage.
Replacement tells
Absence of the peripheral dark ring (indicates solar cell is missing or damaged)
Solar cell that does not charge the e-Crown module after light exposure
Non-uniform or physically damaged solar cell ring
Oil chamber
Original: Identical specification to Type 3; the oil-fill quality standards apply in full.
Replacement tells
Cloudy or bubble-filled oil (same as Type 3 disqualifiers)
e-Crown module
Original: The caseback e-Crown module on the Type 4 is charged by the solar cell rather than a replaceable battery. Confirm the module responds to the synchronization button after light exposure.
Replacement tells
e-Crown module that does not respond after adequate light charging
Physical crown present on the case (Type 4 has none)
Case back markings
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2016 to present
Ressence Type 4 designation
Individual serial number
Ti material designation
30m water resistance
ROCS 4 and e-Crown module references
Movement tells
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The solar cell charges the e-Crown capacitor; leave the watch in natural light for 20 minutes, then test the e-Crown synchronization function.
Both oil condition and e-Crown function need to be verified; a Type 4 with failed e-Crown or degraded oil requires Ressence service.
The base ETA 7001 movement is standard; the ROCS 4 and e-Crown modules require Ressence-trained service.
