I think it depends on whether you think that the difference between a 5R movement (spring drive, used in Prospex) vs. the 9R movement (GS only, I believe) is a real difference or if they're both "GS movements". As far as I know, the only difference between the movements is finishing style and a different rotor. There are other movements with similar minor distinctions (e.g. 9S85 vs 8L55); I think it's a reasonable point from the consumer standpoint that you can get watches in different brands and styles (Prospex vs GS) but with very similar movement quality.

 

FYI, the hi-beats in the non-GS lines are not regulated.

 

To follow up, I own two Prospex with undecorated versions of the GS movement.

The first is the MarineMaster 300M, SBDX001.

As quoted in the attached article, https://monochrome-watches.com/weekly-watch-photo-seiko-marine-master-300/,

"The movement is caliber 8L35, which is an undecorated and unadjusted version of the high-end Grand Seiko caliber 9S55. It’s rhodium-plated, has 26 jewels, beats at 28,800 vph (or 4 Hz), has 50 hours of power reserve, has a hacking function and has automatic winding. Compared to caliber 9S55 this caliber 8L35 has an increased balance wheel. Although Seiko says it’s regulated to -10 and +15 seconds, most owners report a daily deviation of well within COSC specifications."

BTW, I absolutely love this watch. I own lots of very nice vintage pieces, but this is one of my daily wearers. See some other articles.

https://www.fratellowatches.com/hands-seiko-marinemaster-300-sbdx001-review/
https://wornandwound.com/10-days-seiko-mm300/

 

The second is the Emperor Tuna, aka the "Hockey Puck", SBDX 011. This is the big bad daddy of dive watches....

The movement is also an 8L35, the undecorated version of the 9S55. See the following article, https://wristreview.com/seiko-marin...r-sbdx011-the-benchmark-for-all-dive-watches/

"One of the documents that came with this watch highlighted the caliber of the movement used in this model. The 8L35 in an automatic, windable and hackable in-house movement by Seiko. Using 26 jewels, operating at 28,800 bph and a power reserve of 50 hours, this movement is one of the top line movements that Seiko reserve for only its best models, namely the Grand Seikos. In this particular case, the SBDX011 is deemed to be Seiko’s best-in-class, hence it’s right to use the 8L35. In fact, the 8L35 is an undecorated variant movement similar to that of the 9S55 Caliber.

Seiko claims the watch is +/- 10 to 15 seconds a day but as in most cases, Seiko’s actual accuracy is better. In a number of reviews made about this watch, the accuracy of +/- in seconds should be measured in months instead of days. For example in an August 2008 article by Ariel Adams, he said the 8L35 has been better than even chronometer ratings with accuracy clocking in at +/- 10 to 15 seconds a month. In another article written in February 2010 by @bigrustypig, he mentioned accuracy of +12 seconds per month."

See also the following article:https://www.fratellowatches.com/seiko-prospex-marinemaster-1000m-sbdx011-the-hockey-puck/

M

 

The casework, dial design and finishing along with the usual 'Zaratsu' polishing pushes GS up there imo. I've had several and keep going back to them. My only gripe is with their bracelets. The clasps and overall tolerances within each links could be a tad better.

 

I've always been pretty enamoured by the Grand Seikos both vintage and modern alike! My go to for dress watches

The workmanship is astounding and now sadly even the vintage GS prices have already gone skyhigh.

 

Mine...

 

I had a chance to try on the SBGW231 at the local AD this past Saturday. I liked it a lot, but the alligator strap was pretty ugly. (image ©Grand Seiko)

 

Love the finishing on the Grand Seiko. Photographs hardly do them justice. The best I could get is the reflection on the lower left lug in this image. Have to look to see where the edge of the watch is. Got this one for my son as an 18/21st birthday present. He was not into watches as many of his age don’t wear watches. With the buying process and trying on numerous watches he is now a fan of watch wearing. I’m a bit of an omega fan myself but will get a spring drive one day.

 

I still need to manage to make my way to a GS boutique... but they are sure getting more expensive.

 

Have tried one on too. Loved it, a bit boring but very classic - what didn't you like about the alligator strap? the OEM one seemed fairly generic to me, just black.

 

Since starting this thread 3 years ago I've finally jumped onboard the GS train, love this SBGW231 on a bracelet!

 

Big congrats! Looking very spiffy on the BOR bracelet

 

beautiful bracelet mate, very happy I picked one up with it. Maybe not quite as good in terms of build quality to the modern rolex jubilees, but it's close. much more vintage in aesthetic on the GS.

 

Congrats! I may also be ready to get on board with a GMT (haven't had one yet) from GS, and am thinking about these 2 from takuyawatches - the SBGJ235 blue dial one (boutique only) has a 1.5K premium over the SBGJ201 white dial one (6,325 vs 4,825).

 

The Blue Mount Iwate dial is my favorite, if it wasn't for this particular case shape I might have already gotten it.

 

I too prefer the blue dial, but already have blue & black dial watches so considering the white dial

 

nice one!

I think blue and white/silver are grand seiko's best dials, they compliment the high polish hands and indices very well. can't really go wrong!

 

Rather partial to the old ones myself. Could they get better

 

I'd say GS was prettaayyyyyy sweet even in 2011. Here's my SBGW033.



Recently sold for insane in NY