Why are metals shiny?

 The gilded cross on the top of the horse fountain was catching the light. I realised I'd never really thought about why metal reflect. Obviously they must absorb and reemit the photons that come towards them, but why shiny rather than dull. Even dull white surfaces are reflecting something - though that is diffuse reflection. I was interested in these answers https://www.quora.com/Why-are-metals-shinier-and-more-lustrous-than-non-metal-elements especially the one that links it to the layer of metal oxide. But I am also wondering if it is because the layers in the metal allow for a smoother surface and thus more specular reflection - the firing of the photons back in a more unified direction.