Side by side

Serica Ref. 5303 Diving ChronometervsBorealis Watch Co. Estoril 300 GMT

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
Estoril 300 GMT
Borealis Watch Co.Estoril 300 GMT
MSRP $600

At a glance

11 of 29 specs differ
Diameter
Ref. 5303 Diving Chronometer39mm
Estoril 300 GMT41.50mm
Power Reserve
Ref. 5303 Diving Chronometer42h
Estoril 300 GMT40h
Water Resistance
Ref. 5303 Diving Chronometer300m
Estoril 300 GMT300m
MSRP
Ref. 5303 Diving Chronometer$1,768
Estoril 300 GMT$600

Full specifications

Case

4 specs
Diameter
39mm
41.50mm
Thickness
12.2mm
13.5mm
Lug-to-Lug
46.5mm
47mm
Lug Width
20mm
20mm

Crystal & Dial

3 specs
AR Coating
Yes
Inner
Dial Color
Enamel Black
Black
Lume
Super-LumiNova
BGW9

Movement

3 specs
Caliber
M100 COSC
Miyota 9075
Power Reserve
42h
40h
Complications
COSC
None

Pricing

1 specs
MSRP
$1,768
$600

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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.

Borealis Watch Co. Estoril 300 GMT

Owners widely praise the Borealis Watch Co. Estoril 300 GMT for its excellent value, robust build quality, and crisp dial, with reviewers highlighting its exceptionally bright BGW9 lume and dive-ready ceramic bezel. Some owners appreciate the brushed and polished finishes, though one owner noted a desire for a white-painted second hand. The included NATO strap is considered too thick with a loose weave, and the sapphire bezel insert is seen by some as a minor aesthetic departure from its inspirations. Overall, owners rate the Borealis Watch Co. Estoril 300 GMT highly for its impressive build quality and value.

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