For me, and technically every shade between black and white is gray, even if you visualize it shiny. If I'll have to visualize silver on me than maybe I'll visualize it with a texture, like if that something, like the chakra would be a pyramid of silver metal.
I mentioned the Sun in the context that it can be used as a light source for visualization, but I might haven't been clear.
And again, especially for a beginner, because you might be able to visualize light without a light source, but white can easily turn gray if you can't properly visualize light, so a light source is needed. But even than, I had the problem that my eyes got used to the light after like 5 minutes, and I could hardly visualize light/white properly.
Now, the situation is a bit better because I'm able to clean myself properly without any light source, but for the AoP I rather use one because I still can't confidentially visualize light that much, it's rather that I can visualize colors better, but not that shiny.
White gold also turns easily into orange or yellow, but it's much safer than white turns gray.