Under the gold is brass, and brass isn't black. It's more likely crud in-between the lacquer and the gold plating. You might try polish on the black area. But if the black is under the lacquer.....Not sure what the black marks are or how to get rid of them.
The head you have is a New Deluxe, but without the handle it's a bit difficult to say what the razor is. ;-)Another question, does anyone know what model this is?