Sapphire, 200m, a screw-down crown and an in-house automatic that hacks and hand-winds — both of them. Then one costs about twice the other, and the spec sheet barely explains why.
Buy the Orient Kamasu unless you want the extra 30 hours of reserve and the published accuracy figure. Both have sapphire, 200m, a screw-down crown and an in-house hacking automatic, and the Kamasu is thinner and 3mm shorter across the lugs. The Alpinist SPB317 buys you a 70-hour 6R35, a stated plus 25 to minus 15 seconds a day, and a published $296 overhaul price — against Orient's three-year warranty and no service price at all.
This is the comparison that tests whether this site's scoring means anything. The Seiko Prospex Alpinist SPB317 is the highest-scoring watch we cover. The Orient Kamasu is the one we call the best value in its category and not close. They are separated by roughly double the money, and by almost nothing on the four specifications that decide durability.
Both have a sapphire crystal. Both are rated 200m with a screw-down crown. Both run an in-house automatic — Seiko's 6R35, Orient's F6922 — that hacks and hand-winds. Both makers state three years of warranty. On the numbers that stop a watch being thrown away, they are the same watch.
What the Alpinist adds is 30 hours of power reserve, a published accuracy tolerance, and a published price for the overhaul it will eventually need. Whether those three are worth the difference is a real question, and the answer depends on how you wear watches rather than on which is better.
On prices: every buy button on this page reads its figure from the live price layer and stamps the date it was checked, or else reads "Check price on Amazon". No price is written into this text. Service figures quoted here are the manufacturers' own published rates.
How we picked
We have not worn these watches. What follows is what we checked instead, on documents you can open yourself — the same criteria, in the same order, on every roundup on this site. The full method is on the methodology page.
01What is actually identical
Sapphire, 200m, a screw-down crown, an in-house automatic that hacks and hand-winds, and a three-year warranty from both makers.
02Power reserve
70 hours against 40. The honest test is whether your watch sits still from Friday to Monday.
03Published accuracy
Seiko states plus 25 to minus 15 seconds a day for the 6R35. Orient publishes no tolerance for the F6922.
04Cost to keep
A 6R overhaul is $296 on Seiko's published list. Orient publishes nothing at any tier, so an overhaul is a quote.
05Fit
46.9mm against 46.8mm of lug-to-lug, 12.3mm against 12.8mm thick. These two are closer in size than the diameters suggest.
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Quick picks
Ranked on the Keep Score below — six published specifications, weighted identically on every page. The last row is the one we would not buy.
Keep Score is arithmetic, not opinion — six published specifications, weighted the same way on every page. The formula is on our methodology page, so you can re-run it yourself.
It gets every durability specification right at a price where Seiko's own 5 Sports line still fits Hardlex: a sapphire crystal, 200m, a screw-down crown, a 120-click unidirectional bezel, and an in-house caliber that both hacks and hand-winds.
Orient states three years of warranty — the same as Seiko here, and longer than Hamilton or Tissot give you. The lug-to-lug is 46.8mm on a 41.8mm case, which fits a wider range of wrists than the diameter suggests.
The reserve is 40 hours, so it stops over a weekend if you take it off on Friday evening. Orient publishes no service price at any tier, so an overhaul is a quote rather than a number — and that is the one axis where the Alpinist is clearly ahead.
On paper this is the best value in the category and it is not close: sapphire and a hacking, hand-windable in-house caliber at a price where Seiko still fits Hardlex. Orient's three-year warranty is longer than Hamilton's or Tissot's.
Manufacturer specifications for the Orient Kamasu RA-AA0004E39B
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70 hours is the practical difference: put it down Friday night and it is still running Monday morning, with the date correct. The Kamasu will have stopped.
This is where Seiko starts publishing an accuracy figure — plus 25 to minus 15 seconds a day — and where the 6R family's published overhaul price of $296 applies. A number you can plan for twenty years ahead is worth something real, and almost nobody at this level provides one.
It is also 12.3mm thick, half a millimetre thinner than the Kamasu, with a 46.9mm lug-to-lug. The catch is simply the price: for roughly double, you are buying reserve, tolerance and service transparency, not a tougher watch.
This is where Seiko starts publishing an accuracy figure (+25/-15 seconds a day) and fits sapphire. A 6R35 overhaul is $296 against $176 for a 4R36 — a real difference, and one you can plan for.
Manufacturer specifications for the Seiko Prospex Alpinist SPB317J1
Movement
Seiko 6R35, automatic with manual winding, 24 jewels, +25/-15 sec per day
It fails this comparison on the crystal: Hardlex, not sapphire. We list it because it answers a question neither of these two does.
The Turtle carries Seiko's diver's marking — the ISO 6425 regime — which neither the Alpinist nor the Kamasu does. If the watch is going to be dived rather than swum in, this is the cheapest honest route to a certified watch, on the cheapest published service path there is at $176.
45mm and a cushion case make it the biggest of the three by a clear margin. On a small wrist it is not a candidate.
Seiko rates this at 200m as a diver's watch, not merely water-resistant — screw-down crown, screw case back, unidirectional bezel. The 45mm figure is misleading: the cushion case has no protruding lugs.
Manufacturer specifications for the Seiko Prospex Turtle SRPE93
Movement
Seiko 4R36, automatic with manual winding, 24 jewels
Read from Seiko Watch Corporation's and Orient Watch USA's own product pages.
Seiko Alpinist SPB317
Orient Kamasu
Movement
Seiko 6R35, in-house
Orient F6922, in-house
Hacks / hand-winds
Yes / yes
Yes / yes
Power reserve
70 hours
40 hours
Published accuracy
+25 / -15 sec per day
Not published
Case
41mm, 12.3mm thick
41.8mm, 12.8mm thick
Lug-to-lug
46.9mm
46.8mm
Lug width
20mm
22mm
Crystal
Sapphire
Sapphire
Water resistance
200m
200m
Warranty
3 years
3 years
Published overhaul
$296, 6R family
None published
Read from Seiko Watch Corporation's and Orient Watch USA's own product pages.
The 30 hours, and whether you will notice
Power reserve only matters at the weekend. If you wear one watch every day, 40 hours and 70 hours are the same watch — both are running when you pick them up. If you rotate, or you take the watch off on Friday evening and reach for it on Monday, 40 hours means resetting the time and the date and 70 hours means not having to.
That is the single most practical difference between these two, and it is a question about your habits rather than about the watches. Our long power reserve page ranks the whole category on the same measure.
A published accuracy figure is not the same as being accurate
Seiko stating plus 25 to minus 15 seconds a day for the 6R35 does not mean the Orient is worse. It means Seiko has committed to a tolerance in writing and Orient has not. In practice a well-regulated F6922 and a well-regulated 6R35 land in much the same place.
What the published figure gives you is a standard to hold the maker to. If a brand-new watch is running outside the stated tolerance, you have grounds for a warranty regulation. Without a published figure, you have an opinion.
The service price is the real gap
Seiko publishes a full overhaul list by caliber: $137 for a 7S, $176 for a 4R, $296 for a 6R, $373 for an 8R. Nobody else at this level does. Orient publishes nothing at any tier, including its upper Orient Star line where the movements are more complex.
Over twenty years and two overhauls, $296 twice is a known cost on the Alpinist. On the Kamasu it is two phone calls you cannot make yet. That is not an argument that the Kamasu is expensive to keep — it may well be cheaper — it is an argument that only one of these two lets you plan. Our cost of ownership page does the arithmetic across the whole site.
Neither is a certified diver
Both are rated 200m and both have a screw-down crown, which covers swimming and snorkelling without argument. Neither carries a diver's certification, which is a tested regime rather than a pressure number — resistance to salt water, shock, magnetism and thermal shock as well as depth.
If that marking matters, the Seiko Prospex Turtle is the cheapest way to get it and the Turtle versus Seiko 5 Sports page explains what it covers. The Alpinist is listed on this site under dive as well as field because it is rated for the water, not because it is certified for it.
Which to buy
The Kamasu, unless one of three things is true: you rotate watches and want to pick it up still running, you want a maker's accuracy figure in writing, or you want the overhaul price known before you buy. Those are good reasons and the Alpinist delivers all three — but they are not durability, and the Kamasu loses nothing on durability.
Is the Seiko Alpinist SPB317 worth twice the Orient Kamasu?+
Only for three things: 70 hours of reserve against 40, a published accuracy tolerance of plus 25 to minus 15 seconds a day, and a published $296 overhaul price. Both have sapphire, 200m, a screw-down crown and an in-house hacking automatic.
Which is bigger on the wrist?+
They are almost identical. The Alpinist is 41mm with a 46.9mm lug-to-lug and 12.3mm thick; the Kamasu is 41.8mm with a 46.8mm lug-to-lug and 12.8mm thick. The Alpinist is marginally thinner, the Kamasu marginally wider.
Does the Orient Kamasu have a published service price?+
No. Orient publishes no US service list at any tier, so an overhaul is a quote. Seiko publishes $296 for a 6R overhaul, which is the Alpinist's caliber family.
Do both movements hack and hand-wind?+
Yes. Seiko's 6R35 and Orient's F6922 both stop the seconds hand when you pull the crown and both can be wound by hand. That was not true of older Orient calibers, which is why it is worth stating.
Are either of them certified dive watches?+
No. Both are rated 200m with a screw-down crown, which is more than enough for swimming, but neither carries a diver's certification. The Seiko Prospex Turtle is the cheapest certified option on this site.
Sources
Every specification and figure on this page came from one of these documents. Where a manufacturer does not publish something, the page says so rather than filling the gap.
