Question

Generally metals are lustrous. Do all lustrous materials are metals​

Answer 1

Metals are lustrous when polished, that is simply a characteristic of metal as opposed to mineral (although many minerals can be polished, to high luster). Luster is the way light interacts and reflects off of a surface. Metals recognized for their brilliant luster include gold, chromium, platinum, copper, and silver.

Metal which is non lustrous is SODIUM (Na).