When we speak about GMT underline dial, there is not only one, but three different versions.
1/ The Chapter Ring:
One from 1960:
One from 1963:
2/ The non Chapter Ring: Swiss only, deep black, hard to find in nice condition, as most of the dials I've seen came wit spots, bubbles and so on...
Credit picture: Only Vintage Watches ( I think ).
3/ The Non Chapter Ring " Double Swiss ". At 6 o clock you will notice one Swiss mention above the other. Hence the nickname " Double Swiss ".
Easier to see on this picture:
( Credit pictures: Andy Shear ).
As you can see, the chapter ring and the double swiss have centered luminous indexes, while the Swiss only has luminous indexes which touch the minute ring.
The Double Swiss has bigger luminous indexes than the Chapter Ring.
All is a matter of condition, as always, but there is a hierarchy among GMT underline dials. At equal condition, the more sought after is the Double Swiss, then the non chapter ring Swiss only, and the Chapter ring.
It seems that the " Underline " detail came as early as 1960, and ended in late 1963.
What does this detail mean, that is an endless debate, and I have no fixed nor clear opinion here. As for the Exclamation Dot as 6 o clock.
Do we really need to explain all the mysteries, or isn't it better to keep a part of untouched mystery?
I must say that I have a certain fascination for the Double Swiss, because of its specificity: I love the big round and centered luminous indexes.
But I would be very happy with any of them.
Best,
Nicolas
But I would not be objective to say that I don't like it!
Best, Damjan, and thanks for your input.
Nicolic.


First, I never saw a 6542 underline, but why not, since there are some 6542 Exclamation Dot.
Then, as for the period, I saw several " - " from 1960, several quartals. And now that you wrote it, some early 1964 ones... A few.
When were the " - " 6542 dials released? Do you happen to know?
Best, Amico.
Nicolas.



Great pair!
Best,
Nicolas
Is your SYL around 1964?
Best,
Nicolas
But when it comes to SYL and the GMT MASTER, I am totally crazy, and if you add the fact that it is from 1964, I am mad to depth... Or almost.
No, seriously, I never found a GMT MASTER from 1964 with a nice dial. Yours is a delicious exception!
As for the Underline Double Swiss, well... A superb piece, for a connoisseur. Undisputably.
Best, Eko.
Nicolas