sub dial spacing (or indicie length) are the instant tell on those.
Subs are more difficult because there are so many fakes. Modern (ceramic bezel insert) sub fakes are damn near impossible to tell apart. Even side by side.
I have a replica 116600 seadweller because I couldn’t swing the $11,400.00 when I saw it and tried it on in the store. It is the last SD without a date magnifier and was a short run watch.
But at the end of the day, I tend to wear jangly 60’s and 70’s-era watches much more that the modern ones. The above 1680 does not impress as a “refined” watch at all. My newer Omega Planet Ocean trounces it in every department. But I enjoy the top hat crystal, big magnification of the date window and overall look. It was state of the art in the 60’s and like a classic car, still holds up but does not run in the same races.