Seiko Prospex Sea 1968 Heritage Diver's GMTvsSpinnaker Dumas Automatic
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Measurements
Catalog photos are all shot at the same flattering size. These aren't: every case below shares one millimeter scale.

Prospex Sea 1968 Heritage Diver's GMT

Dumas Automatic
Diameter
42mm
44mm
Lug-to-Lug
48.6mm
48mm
lowest
Thickness
12.9mm
lowest
15mm
Water Resistance
200m
300m
highest
Power Reserve
72h
n/a
MSRP
$1,500
$239
lowest
Movement
Seiko 6R54
Seiko NH35
Case
6 specsCrystal & Dial
3 specsMovement
3 specsPricing
1 specsReviews
Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.
The Seiko Prospex Sea 1968 Heritage Diver's GMT is widely praised for its build quality, finishing, and value, with owners noting its comfortable wearability and attractive aesthetic, particularly the silver/white sunray dial and blue ceramic bezel. The improved bracelet clasp with excellent micro-adjustment is a recurring positive point. Some owners report accuracy figures of +3 seconds per day or +/- 5 seconds per day, exceeding the movement's stated range. However, the GMT functionality is considered secondary to its dive watch capabilities by some, with the GMT scale being difficult to read and the caller-style GMT movement being a drawback for certain users. The dial contrast is also noted as lacking by some, and the crown at 4 o'clock is undesirable for a few. On balance, owners and reviewers rate the Seiko Prospex Sea 1968 Heritage Diver's GMT highly for its blend of dive watch character and GMT functionality, offering significant features for its price.
Owners widely praise the Spinnaker Dumas Automatic for its robust build quality, attractive textured blue dial, and excellent finishing for its price point. The watch is noted for its comfortable wearability, attributed to a short lug-to-lug distance, and owners report positive experiences with the Seiko NH35 movement. Some owners mention a mineral crystal instead of sapphire, a bracelet with a learning curve, and a crown that feels slightly small. Overall, owners rate the Spinnaker Dumas Automatic highly for its aesthetic appeal and solid construction at a fair price.
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