I own a GS SBGW 231 and SBGW 255. Basically they are same except the latter is limited edition. Curiously I found some “marks” on both watches in between the bezels and the sapphire crystals. A purist also told me that he found the same marks on his SBGW 231, so I believe it is not an isolated case.
As some said it’s 39.5mm and some said 39mm. (The second and third gen are definitely 39.5mm). And it you could also let me know the lug to lug measurement (48mm?)? I ask because I am planning to acquire one soon but I got a very tiny wrist so the size does matter to me!! Thank you!