>>Coat the exterior of the exposed diamond with sapphire film?
>A thin layer of sapphire, a layer of silicon foam insulation
>and skinned in stainless steel.
Why not a layer of filet mignon? Or even hamburger ...
[Or narwhal horn, or macadamia nut, or scorpion DNA. One obvious possibility is to use a closed-cell diamond foam where the cells are filled with pressurized water. I invite any ambitious engineering student to analyze the strength of the resulting structure... --JoSH]