Case Dimensions: The case width of the 1675 comes in at 39 mm in diameter, 2 mm wider than the 6542 case.
- 1959 – 1967: There were so-called ‘thin cases,’ which maintained the thickness of the 6542 and were approximately 12.7 mm thick from case back to plexi.
- 1967 – 1979: The case thickness increased to 13.0 mm and was maintained until the end of the production run. The case length from lug to lug is 47.5 mm. Source
Case Engravings: The engravings on the 1675 evolve in a similar pattern to those on the 1016 Explorer, as one would assume of two similar watches made by Rolex over the same period. Between the lugs sit the model and serial engravings. The the engraving at the 12 o’clock (top) position has the model number and the 6 o’clock (bottom) position has the serial. There are four variations that occur across the 1675’s model life (picture credit to HQ Milton):
- SN 5xx,xxx – 695,xxx (1959-60): In these early examples, the top position has “1675” on the first line and “Registered Design” on the second line. The bottom position has the serial number on the first line and the second line is either blank or has “Stainless Steel”.
- SN 695,xxx (1960) – 2,8xx,xxx (1970): In this “standard 1960’s” engraving, the top position has “Registered Design” on the first line and “1675” on the second line. The bottom position has either a blank top line or “Stainless Steel” and the serial number on the second line. So far, there is not a clear pattern to the 1960’s watches having the “Stainless Steel” engraving or a blank space. Both are seen throughout the early and later 1960’s, within the same serial batches, and with both fonts types (see below). I don’t have a good enough sample to determine if these vary by country of delivery, which is another possibility.
- SN 2,9xx,xxx (1971) – 6,xxx,xxx (1979): the top position has “Registered Design” on the first line and “1675” on the second line. The bottom position always has “Stainless Steel” on the first line and the serial number on the second line.
- Engraving Fonts: There are three engraving fonts used throughout the run of the model line, which Jose P. and Xeramic have studied in detail. They are Typefaces A, B, and C in the collages below, which are surmised to be used from 1953-1976, 1943-1978, and 1970-1992, respectively. Typeface D is from 1992 onward and should not be seen on the 1675. Credit to these scholars for this work:
Crown: Crowns on the 1675 were Rolex ‘twinlocks,’ 5.3 mm in diameter, and featured the Rolex coronet with an underline underneath. The twinlock crown system has two rubber gaskets. One gasket is inside the crown and compresses against the threaded tube attached to the watch case. The other rubber gasket is located inside the watch tube and encompasses the winding stem. Together, they prevent water and dust from entering the case. While the gasket in the watch tube can prevent water and dust from entering the movement even while the crown is unscrewed, don’t be an idiot – screw down your crown. Source
Crown Guards: Crown guards are found on all 1675’s. They’re generally broken down into two groups – the pointed crown guards (PCG) and rounded crown guards. There are actually two types of PCG and a slow but subtle evolution to the rounded crown guards that changes over the years.
- El Cornino PCG: Italian for ‘the horn,’ these are seen on early models, from the earliest OCC dials until around SN 1.0m. This crown guard type can be found on any chapter ring dial types as well as early non-chapter ring dials. They are notable for the extra facet on the side of the crown guards, which is an extra intricacy that can easily be lost with polishing.
- Broad PCG: These appear to have been introduced around SN 874xxx and were seen until at least 114xxxx. The easiest way to see the difference on these is the lack of the extra facet on the side of the crown guards – also, for polished examples, notice how the lug chamfer starts in a different manner between El Cornino and broad PCGs.
- Note: The Type A and B non-chapter ring gilt dials always are cased with PCGs and can be seen with both PCG types. Early Type C dials are also seen with PCG’s, up to the SN noted above, and then with rounded crown guards.
- Rounded Crown Guards: These ‘standard’ crown guards were upgraded to the shaped/rounded crown guards around 1.1-1.2m and remain on Rolex watches until today. While firm conclusions about their evolution cannot yet be matched to particular serial ranges, it is easy to note that they change as you move from their introduction in the mid-1960s through the rest of 1970s. The 1960’s style has a long and flat top where the first facet starts in line with the edge of the knurling on the crown. This facet moves closer to the case until, in the late 1970s, it starts right at the edge where the crown flushes to the case.
Crystal: All “crystals” for the 1675 are not in fact crystal but a plastic acrylic “plexi” covering.
- Standard Crystal: Designated part Tropic 116 (i.e. T116), these are fitted with a so-called ‘cyclops’ window over the date wheel for ~2x magnification of the date. Original crystals have a rounded edge around the top while service crystals have a large, beveled edge. Aftermarket cyclops crystals often lack the magnification of OEM plexi’s and do not fit flush.
- Non-cyclops: Designated part Tropic 38 (i.e. T38), these were thought to be a service part that could be added at the request of the owner. OEM versions are a sought after option. Source
Lugs: This is a very controversial area. There are more watches having material added and repolished so it is very difficult to tell honest examples from those that have been expertly redone. You need a loupe and a lot of experience to tell for sure. Here are some nice examples to demonstrate the ideals, however, I would be cautious in interpreting how nice a case is before seeing it up close. The first example (pictures 1-4) is worn but honest and the second is barely worn (pictures 4-8). Generally, examples from the early 60’s have more accentuated bevels that get wider near the end of the lug compared to the later matte dials, which generally have the a much more uniform width down the length of the chamfer.