Serial Number Range: 5032xx – 505xxx, 680xxx*
Notes: The first dials of the 1675 retain the “Officially Certified / Chronometer” text of the 6542 gilt printed on the lower portion of the dial. After these dials, all subsequent 1675 iterations are printed with Rolex’s (then) new “Superlative Chronometer / Officially Certified” moniker. This difference stems from the transitional nature of these pieces and signifies that the movement underneath is not the 1565 calibre seen on all later 1675 models but still houses the earlier 1535 (itself somewhat of a transition from the 10xx to 15xx calibre movements) without the microstella adjustment. As this is a transitional period, Type 0 dials have been seen with the newer 1565 movements (usually marked 1560, the base time-only version).
Much of the knowledge about this interesting dial and transitional period is due to the work of Stefano Mazzariol, who deserves our thanks.
Picture Credit: Rolstaff of VRF
*Please note Eric Ku has shown us two OCC dialed examples (1,2) with underlines – one with serial 680xxx, the other is unknown to me. These dials seem to have the same characteristics as the non-underline versions. I would only trust someone like him to verify a piece like this if you come across one.