Seiko · Prospex Sea and Prospex Sea

Seiko SPB317J1 vs Seiko SPB453J1

9 published specifications differ between these two, and 7 are identical. Every figure below is what the manufacturer states for that reference; nothing is inferred from the other watch.

What differs

Specification	Seiko Prospex Diver 200m, 6R35, silicone bandSPB317J1	Seiko 1965 Heritage Diver's Watch, 6R55, 300mSPB453J1
Case	Stainless steel, 41.0 mm	Stainless steel, 40.0 mm
Diameter	41 mm	40 mm
Thickness	12.3 mm	13 mm
Lug to lug	46.9 mm	46.4 mm
Water resistance	200m / 660ft diver's	300m / 1000ft diver's
Bracelet	Silicone band, 20 mm between the lugs	20 mm between the lugs
Calibre	6R35	6R55
Power reserve	Approximately 70 hours	Approximately 72 hours (3 days)
Movement notes	Precision stated as +25 to −15 seconds per day. Stop second hand and date display. Magnetic resistance 4,800 A/m. LumiBrite on hands, indexes and bezel. Total weight 100.0 g.	Precision stated as +25 to −15 seconds per day. Stop second hand function. LumiBrite on hands, indexes and bezel. Total weight 168.0 g.

What is identical

Worth knowing as much as the differences: these are the specifications you cannot use to tell the two apart.

Lug width: 20 mm
Crystal: Curved sapphire crystal, anti-reflective coating on inner surface
Bezel: Unidirectional rotating bezel
Case back: Screw case back
Crown: Screw-down crown
Movement: Automatic with manual winding
Jewels: 24

Stated for one, not the other

These rows cannot be compared, because one maker publishes the figure and the other does not. An empty cell is a gap in the manufacturer's documentation, not a gap in the watch — and not a licence to fill it in from the other column.

Clasp	not stated	Three-fold clasp with secure lock, push button release with extender

What the differences cost you

Each note below follows from the published figures in the tables above — what they mean for intake, for a listing, and for the handover. Nothing here estimates a price or a margin.

Do not describe these the same way

300 metres on the SPB453J1 against 200 on the SPB317J1. Both are more than daily life asks for, so the number is a listing-accuracy question rather than a practical one: quote each watch its own figure, and remember that neither rating survives an unserviced case by itself.

Different movements to verify and to service

The SPB317J1 runs the 6R35 and the SPB453J1 the 6R55. Two consequences at intake: the service history that is normal for one calibre is not evidence about the other, and the calibre is the check that catches a movement swapped into the wrong case. Confirm the movement matches the reference rather than assuming it from the dial.

What to check on each

SPB317J1

Bend the silicone band fully back on itself at both lug ends and look into the crease. Silicone fails from inside a fold, and a flat inspection will miss cracking that is about to become a failure.
Confirm the calibre is the 6R35 rather than the 6R55 used elsewhere in this family. Both are 24-jewel automatics from the same maker, and they carry different reserves.
Weigh it against the published 100 grams. That is remarkably light for a steel 200-metre diver and is largely the band rather than the case, which matters if a buyer intends to fit a bracelet.

SPB453J1

Read the published precision before you time one. Seiko states +25 to −15 seconds per day, so an example gaining twenty seconds daily is inside its own specification and is not a fault to price around.
Test the clasp extender as well as the clasp. It is a moving part with its own catch, it is used over a wetsuit, and it is the component most likely to have been bent.
Turn the bezel anticlockwise through a full revolution and confirm it will not move the other way at all. A unidirectional bezel that turns both ways has lost its safety function.

Sources

Not affiliated with Seiko. Specifications are read from each manufacturer's own published documentation on the dates shown and may change; the manufacturer's current documentation governs.