Side by side

Serica Ref. 5303 Diving ChronometervsSeiko Prospex Sea 1965 Heritage Diver's Watch

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

Ref. 5303 Diving Chronometer
SericaRef. 5303 Diving Chronometer
MSRP $1,768

At a glance

12 of 29 specs differ
Diameter
Ref. 5303 Diving Chronometer39mm
Prospex Sea 1965 Heritage Diver's Watch40mm
Power Reserve
Ref. 5303 Diving Chronometer42h
Prospex Sea 1965 Heritage Diver's Watch72h
Water Resistance
Ref. 5303 Diving Chronometer300m
Prospex Sea 1965 Heritage Diver's Watch300m
MSRP
Ref. 5303 Diving Chronometer$1,768
Prospex Sea 1965 Heritage Diver's Watch$1,300

Full specifications

Case

3 specs
Diameter
39mm
40mm
Thickness
12.2mm
13mm
Lug-to-Lug
46.5mm
46.4mm

Crystal & Dial

4 specs
Crystal Shape
Flat
Curved
AR Coating
Yes
Anti-reflective coating on inner surface
Dial Color
Enamel Black
Black
Lume
Super-LumiNova
LumiBrite on hands, index(es) and bezel

Movement

4 specs
Caliber
M100 COSC
6R55
Power Reserve
42h
72h
Jewels
25
24
Complications
COSC
None

Pricing

1 specs
MSRP
$1,768
$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.

Serica Ref. 5303 Diving Chronometer

Owners widely praise the Serica Ref. 5303 Diving Chronometer for its excellent wearability, definitive style, and smooth, confident bezel action. The dual scale on the bezel is noted as surprisingly useful, and the crown action, winding, and hacking are reported to work perfectly. One owner describes the Serica 5303-3 as gorgeous and unique, though another notes the crown can appear comically large. On balance, owners rate the Serica Ref. 5303 Diving Chronometer highly for its blend of unique design and robust functionality.

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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