About this watch

Reference 136668LB is the Deepsea in 18 ct yellow gold, blue dial under a matching blue Cerachrom bezel. A saturation diver's watch made out of solid gold, which is either the least sensible thing Rolex has done in a decade or the most honest one. Underneath the theatre there is real engineering, and the Ringlock System is worth understanding because nobody explains it. At depth the component under the most load is not the case — it is the crystal, pressed inwards by several tonnes of water. A conventional dive watch asks the middle case to resist that, which is why most pressure ratings run out in the low hundreds of metres. Rolex instead fits a compression ring inside the case and lets the crystal bear against the ring rather than the case. The ring takes the thrust; the middle case only has to hold the ring. The crystal itself is domed sapphire, five and a half millimetres thick, which is more glass than most watches have case. In gold the whole proposition turns faintly absurd, and that is most of the appeal. Forty-four millimetres of 18 ct yellow gold is not a light object, and the depth rating is one that no human being will ever test. The numerals on the blue Cerachrom inser…