Hi Jim :) Someone's probably gonna mention this, and it might as well be me since I just lurk here most of the time.
An object's color is determined by the wave length of the visible light that it reflects most strongly. But atoms do not reflect light at all. Light waves are far larger than an atom, and pass by it as though it were not there.
The visible light that you see reflected from the objects you see around you, is reflected at the atomic level. Specifically, it's the electrons that are doing the reflecting. So it is essentially the surface of the atoms that are doing the reflecting. In reality, all you ever see, or touch, are the electrons in atoms. In addition: Individual atoms also reflect light. Yes, they do that. Here is an example that I found interesting many years ago. I used to make custom knives, and so purchased many books on metallurgy. One book from MIT was a historical review, and it mentioned the manner in which the beautiful colors on King Tut's death mask (coffin cover?) were made. Various alloys containing mixtures of silver, lead, (tin?.. it's been a long time since I mae knives :) ), copper, AND GOLD were described. Those alloys all had one thing in common. After the alloys were made, they were applied to surfaces, smoothed, and then etched. As the etching process progressed, all the surface atoms except the gold ones were slowly etched away. That left little gold "bump" atoms sort of lumped on the surface. Kinda like tennis balls cut in half sitting on a table. Those remaining gold atoms reflected light. The etching depth determined the portion of each gold atom that was sticking out of the surface. This in turn determined the color that the whole surface reflected. And yes, by choosing the alloy components, carefully smoothing the alloy surface, and closely monitoring the etch time, you can get essentially the full visible spectrum to reflect from an alloy surface created and etched as I just described. Portions of individual gold atoms doing the reflecting. Stay wicked :) Sam Pell