Close view on a Rolex Cal. 618 / Type 1
by Volker on May.10, 2013, under General
Used in Ref. 3646 watches from Type A to Type G, the Rolex Cal. 618 movement comes without Incabloc shock protection. Typical for the non-incabloc version is the serif font for the letters A-R (French) and F-S (English) engraved on the regulation device (later versions show “+/-” symbols – see also Type 4).
The central bridge shows the “ROLEX 17 RUBIS” engraving on the left side. This engraving is used only in Ref. 3646 watches from Type A to Type D, as the Ref. 3646 watches from Type E to Type G bear “17 RUBIS FAB. SUISSE”.