Side by side

Formex Reef GMTvsSeiko Prospex Sea 1965 Heritage Diver's Watch

The numbers, the dial colors, the calibers — laid out so you can stop flipping between tabs.

Reef GMT
FormexReef GMT
MSRP $2,235

At a glance

12 of 29 specs differ
Diameter
Reef GMT42mm
Prospex Sea 1965 Heritage Diver's Watch40mm
Power Reserve
Reef GMT56h
Prospex Sea 1965 Heritage Diver's Watch72h
Water Resistance
Reef GMT300m
Prospex Sea 1965 Heritage Diver's Watch300m
MSRP
Reef GMT$2,235
Prospex Sea 1965 Heritage Diver's Watch$1,300

Full specifications

Case

5 specs
Category
GMT
Diver
Diameter
42mm
40mm
Thickness
11.4mm
13mm
Lug-to-Lug
47mm
46.4mm
Lug Width
22mm
20mm

Crystal & Dial

3 specs
Crystal Shape
Flat
Curved
AR Coating
Inner
Anti-reflective coating on inner surface
Lume
Super-LumiNova
LumiBrite on hands, index(es) and bezel

Movement

3 specs
Caliber
Sellita SW330-2
6R55
Power Reserve
56h
72h
Jewels
25
24

Pricing

1 specs
MSRP
$2,235
$1,300

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What people say

Owners + reviewers, side by side

Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.

Formex Reef GMT

The Formex Reef GMT is widely praised for its unique porthole case shape, COSC-certified Sellita SW330-2 movement with good finishing, and comfortable quick-release bracelet with on-the-fly micro-adjustment. Reviewers note its robust construction, impressive specifications, and strong value proposition, with a slim 11.4mm profile accommodating 300m water resistance and an exhibition caseback. However, owners widely report the 53mm lug-to-lug span with male endlinks makes it too large for smaller wrists. Some find the bezel action stiff and potentially slippery, and a reviewer desired sharper finishing and edges, deeming the aesthetic too modernist. The GMT variant sacrifices a timing bezel unless swapped, and one owner notes sharp edges on the crown and crown guard. Overall, owners and reviewers highly rate the Formex Reef GMT for its exceptional value and well-executed features, particularly its bracelet system and COSC-certified movement.

From video reviewers

The watch features a COSC-certified SW330-2 GMT movement, which is visible through a sapphire crystal display case back and beautifully decorated. The watch's water-resistance of up to 300m/1000ft is a notable feature. The 42mm diameter may be too large for smaller wrists.

Seiko Prospex Sea 1965 Heritage Diver's Watch

The Seiko Prospex Sea 1965 Heritage Diver's Watch is praised for its refined engineering and updated features, including a 300m water resistance and a 72-hour power reserve from the Caliber 6R55 movement in a 40mm case. Owners note its better build quality and interesting finishing with a mix of polished and brushed surfaces. The "Tranquil Teal" variant features a jewel-toned dial with a rippling-water pattern. However, some owners consider the price too high, and concerns exist regarding the accuracy of the 6R movements, with some reporting theirs run slow. One review notes a reflective dial that impacts legibility. On balance, owners and reviewers appreciate the Seiko Prospex Sea 1965 Heritage Diver's Watch for its refined design and improved specifications over previous generations, despite some reservations about movement accuracy and price.

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