Is Stefan–Boltzmann law valid for light reflection

[sawer]

I know emissivity parameter of Stefan-Boltzmann equation is related to both "absorption" and "emission" of the material.

But is it related to "reflection" property of an object?

If not what is the parameter that makes an object shiny?

 

[mfb]

But is it related to "reflection" property of an object?

Not directly.

If not what is the parameter that makes an object shiny?

Coherent absorption and re-emission. You can get reflection (instead of random scattering) if waves are a good model for the interaction of light with the material.