It almost seems as if that little bit of black on the side was a skin inside the mold, yet it somehow still looks like a laminate.
In one pic it looks as though the darker side, not the black, is made by using glitter. It seems as though the non- darker side has very little glitter. Or maybe that darker side is some sort of black pearl mixed in the red. Or maybe just a pin tip amount of black stirred into the red, with lots of glitter?
I think there are a few ways you can make this color combo. None of them easy. Maybe easy isn't the word, time consuming seems more like it. If you attempt these , let us know how it works out.