Question

Why does metal produce luster and is present in some limited colours

Answer 1

It has to do with the way light and electrons on the surface of metals interact. It goes like this; the outer electrons in a metal are almost not bound to any individual atom, thus are relatively free, and are concentrated on the surface. This electrons (electron density) tend to oscillate at a collective frequency. As they oscillate they prevent any incoming light from entering the metal or passing through it. Consequently, the incident light is reflected back. Although a lot of materials also reflect, only those with a lot of nearly free electrons can reflect huge amount of light. It is the intensity of this reflected light reaching our eyes that make it appear lustrious