When deconstructing a Solo Spacefarer nosecone, it will drop 2400 kg of steel, and 385 kg of diamond, no matter the construction material.
Steps to reproduce.
1) Build a rocket platform, and an engine.
2)Build a spacefarer nosecone.
3) Inspect the interior
4) leave the rocket and return to the asteroid via the starmap
5)Deconstruct the nosecone.
6) Steel and diamonds drop