Credor Seiko GCAY999 – 4S79 Handwinding

I would like to share yet another knock-out beauty that came into my possession recently.


The addition of this watch helps to build up both my Credor collection and also my 4s movement collection, having now in my possession the 4s15, 4s25 (already sold, but otherwise similar to 4s15), 4s36, 4s29 and this most recent 4s79 movement. Thus this continues my ongoing fascination with the 4s movement, which is now discontinued by Seiko.

Functionally, the 4s29 and 4s79 are very similar movements, both being handwinding only, with subsidiary seconds hand located at the 6 o’clock sub-dial and with a power reserve complication located at the 9 o’clock position. These movements are non day/date. The Credor 4s79 movement is rated to +15/-10 sec/day, while the Brightz 4s29 movement is rated to +25/-15 sec/day. As with most Credor watches released in the late 90s and early 2000s, the movement is gold plated (btw which makes them a great buy since you get a gold plated high grade movement compared to the recently issued Credor watches which are easily twice the price). This is in stark comparison to the Brightz 4s29 movement, which pales in comparison. Interestingly, the 4s79 movement has 31 jewels compared to the 4s29 movement with only 29 jewels, despite having the same complications and dial layout.

image (6)CAM01404

Other similar models containing the same movement include the following (all pictures below are taken from the internet and watch forums):

Chronometer variants (GBAY992 LE 500 -yellow gold and GZAY 999 LE 20 – white gold)
These are the only watches with the 4s79 movement that are certified “Chronometer”. These are also the only watches in recent Seiko history (1980s onwards) that were certified “Chronometer” and are labelled as such at the 3 o’clock position. Please go to this link for an interview with the Seiko employee who adjusted these Chronometers, and went on to work on the regulation and adjustment of the first modern Grand Seikos!

Subsequently, the modern Grand Seiko line was relaunched in 1998, and Seiko’s own GS requirements (which are stricter than COSC “Chronometer” standards) were put in place.  These are also the only watches containing the 4s79 movements that have a display caseback, as far as I’m aware. Beats me why all the other 4s79 models have solid case backs when all the 4s79 movements are similarly decorated to such a high degree.

GZAY999 black chronometer back GZAY999 black chronometer GBAY992 white chronometer back GBAY992 white chronometer front

Platinum variant (GBAY999 and 1 undetermined model)

GBAY999 platinum variant front

Platinum variant front Platinum variant back

Solid gold variant (GBAY996)
gbay996 solid gold front GBAY996 sold gold back

Bracelet variants (GCAY995, GCAY994, GCAY992, GCAY991, GCAY 990) 
GCAY995 GCAY994 2 GCAY992 GCAY991 gcay990

2-tone variant of my model (GCAY996)

Minimalist variants (GCAY987- white dial and GCAY 989 – black dial)



The case is a svelte 8mm mainly due to the hand winding movement. Lug size is 18mm. Case finishing is not of a comparable level to my Ananta nor my Credor GMT, I would also put it just below my Credor Phoenix which was released in the same period, but belongs to a different Credor family.  I would judge it on a comparable level to the Brightz family, due to its simple case design and finishing, which is less complex and easier to achieve.


However the bezel is certainly a work of art. The Roman numerals are etched into the bezel itself, which adds a dash of class and a dose of casual wear-ability to an otherwise pretty sober dress watch. The bezel is also highly polished with 2 tracks running along the inner and outer circumstance of the bezel, framing the roman numerals between them.


The crown is signed with the Credor logo, and is completely polished.

Solid case back, which is in total contrast to the front and hides the fantastically decorated movement, which is a shame.



The dial is a satin silver, with no patterns/markings whatsoever on the surface, and is covered with a flat sapphire crystal.

The words “Credor” and “Seiko” are printed neatly at the 12 o’clock position, with no signs of bleeding, while the highly polished Credor logo is applied above the printing. Simple silver sticks run along the circumference of the dial and is used in a highly effective manner to indicate the hour markers. A train track is also found on the chapter ring to indicate the minutes, but otherwise is pretty much un-obstructive during daily usage.

Hands, sub-dials and power reserve

20141003_141612The hour and minute hands are finished very similarly to the hour markers, and together with the satin silver dial, tend to make it hard to read in strong sunlight. However due to the high polish factor, it also makes it easy to read in low light as the hands and hour markers catch and reflect light effortlessly. The hour and minute hands are of the same width, but different lengths.

Correspondingly, the subsidiary seconds hand appear to be a minimised version of the hour or minute hand, as it retains the same shape and polish factor. The subsidiary dial is framed with a silver border and the arabic numerals are printed very neatly on the inside. There is also an additional silver border running internally that adds visual interest and also mirrors how the power reserve is presented. Due to the size of the second hand which beats at 8bps/28,800 bph, the motion will always appear smoother than a watch with a central second hand. This also contributes to a look of “stillness” when taking a quick glance at the watch. Some people may not like it, but I do like how this “stillness” adds to its subtle factor, very much like how most people are not even aware of the Credor branding, and how high it ranks in the Seiko hierarchy.


The power reserve can be found at the 9 o’clock position. Mirroring the layout of the subsidiary seconds, it is also framed by a silver border, with another internal silver border neatly underlying the crisply printed digits which indicates the reserve left. The “0” is in red which indicates empty reserve. One can note that the power reserve complication distinctly takes on an oriental fan shape, which plays to its Japanese heritage.

If one observes carefully, one will be able to spot “dots” located between the digits, indicating the half way point between each hour marker, for example 35 hours, 25 hours, and so on. You will also notice that the “dots” are not located centrally between the printed digits. This is not a mistake because the reserve does not run down lineally. Refer to this link, for an explanation of the Oris non-linear power reserve indicator which works in the same manner. These are the minor attention to details that adds up to the cost of the watch.


With its satin silver dial and high polish factor, this is certainly the most dressy of my Seiko/Credor watches. It also embodies the value proposition when it was first released, having come with a gold plated high grade movement and impeccable case finishing at its price level. Given that most mechanical watches nowadays are automatic, having a handwinding only watch is something that not every collector has the opportunity to own. At this point in time, there is no handwinding only movement below the Grand Seiko range, which makes the 4s79/4s29 movement a highly desirable movement to add to one’s collection, at the right price, if they can be found at all.


5 thoughts on “Credor Seiko GCAY999 – 4S79 Handwinding

  1. Pingback: The Credor Thread - Page 3

  2. Pingback: So what do you get when you send a Credor for an overhaul/servicing with Seiko Japan? | musingsofawatchaddict

  3. Pingback: Vintage Seiko Buying Experience | musingsofawatchaddict

  4. I just acquired a two-tone GCAY996 and had to comment because this is where I first heard about this line 🙂

    Funny thing is that 99% of the pics on the internet had it wrong. It has a finely woven gold dial, with white sub-dials (power reserve & small second) contrasting nicely. Probably the most funky “gold watch” I’ve seen.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s