Kiebitz?

I acquired a partial set of 3 out of 7 razors for what would be a 7 day set. the scales are black for the most part with the bottom looking like mother of pearl inlay, though I am not sure if it is real. There is a metal "kiebitz" overlay where the mother of pearl meets the black. The tang is stamped with a deep 150 and then it says "kiebitz" garantie. I have the Sunday, Tuesday, and Wednesday razors.

Attachment 287749Attachment 287750Attachment 287751Attachment 287752

Pictures, I don't know anything about them other than appearance

Very nice.
Lightly run the scales on a tooth, if it feels like high grit sandpaper, its MOP. If it slides effortlessly, plastic.

I'm pretty sure it's plastic.