Need you experts- question re: ceramic cases

I was poking around in some old threads, and came across a statement about the Dopplechronograph cases, the ones on the ref. 3786 (the smaller diameter) vs. the larger ref. 3799 (for the Top Gun and Carleson models). This person said the case was 'solid' for the 3786, but for the larger cases the ceramic was just a covering over a core (implied something else).
I find this hard to fathom, and believe these cases must be solid, all of them.
But what do you experts say?
Thanks, NElson