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Grand Seiko Elegance GMT "Moondrop" SBGM257

Reference SBGM257. A sheet to take with you: the numbers to check the watch against, what to look at, and what to ask. It does not authenticate anything and it does not tell you whether to buy.

Check the numbers

Measure or ask. A watch that does not match these is not necessarily wrong, but it is a question worth the answer.

Anything above marked not recorded is a gap in this catalog, not a property of the watch. Do not read a blank as a zero.

Before anything else

A steel Elegance GMT on the 9S66, which is a conventional in-house automatic rather than a Spring Drive. The most useful check is that the GMT is a true traveller complication and behaves like one, and the most important thing to know is that this watch is not built for water.

What to look at

1. movement True traveller GMT behaviour
   Correct The local hour hand jumps in one-hour steps without disturbing the minutes or the 24-hour hand
   Red flag The 24-hour hand moving while the local hand stays fixed, which is the wrong caliber or a fault
2. dial Zaratsu-polished markers and the spiral texture
   Correct Distortion-free mirror facets on the markers and hands, with the dial pattern pressed rather than printed
   Red flag Any waviness in a polished facet, which is the tell Zaratsu polishing exists to avoid
3. movement Caliber 9S66 through the display back
   Correct Automatic 9S66 at 28,800bph, roughly 72 hours from full wind, seconds hacking on the crown
   Red flag A reserve well short of 72 hours, or seconds that keep running with the crown out
4. case Case back screws and gaskets
   Correct Six screws present and even; the modest rating depends on intact gaskets
   Red flag Mismatched or burred screws, which suggests the case has been opened casually

Known issues on this reference

• Grand Seiko itself rates this only as "splash resistant", and the press coverage puts it at 30m. Either way it is a dress watch: it should not go swimming, and a seller describing it as water-resistant in any general sense is overselling it.
• The 9S66 is a TRUE GMT: the local hour hand jumps independently in one-hour steps while the 24-hour hand stays put. A watch where the 24-hour hand moves instead is either faulty or not this caliber.
• The box-shaped sapphire is more expensive to replace than a flat crystal and its distortion at the edge is correct rather than a fault.

Parts that are commonly replaced

• The crocodile strap is consumable and is replaced routinely; confirm whether the folding clasp is the original Grand Seiko part.
• Box sapphire crystals are replaced after impact and are not a generic part.

Ask the seller, whatever the watch

• When was it last serviced, by whom, and is there paperwork?
• Has the case ever been polished?
• Which parts are not original to it?
• Do you have the box, papers and the original bracelet or strap?
• Why are you selling it?
• Can I see it in daylight, and can I take a photo of the caseback?

What this sheet is standing on

The specifications above are sourced to grand-seiko.com, monochrome-watches.com. What else the catalog does not know.

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