Is this how the plastron of my russian should look?

[TriterTortoise]

Dont worry about the brown specks, its just substrate.

Anyways his plastron is black, is that normal?. I see pictures and their bottoms look the same color as the top shell.

 

[wellington]

Some are very dark some are not. Looks good

 

[Pearly]

I can't really tell by this picture if it is smooth. If it has irregular shaped rough pits (like something is eating at it) than it maybe shell rot. Could you take couple more pics of it from little different angle so the light of the flash doesn't glare so much?