... is due to the part's material. Traditionally, the Marine series watches have a polished titanium back. Maybe - I am far from being authoritative on this - it is too difficult to combine the DLC with titanium?
Anyway, thanks for the great pictures! personally, I have some mixed feelings, regarding the Black Ocean. When I have a sports watch, I demand a good legibility, and dark grey SuperLuminova just does not fulfil this requirement for me.
Regards,
Marcus