Cobalt Bule Sulphide Marble?

I was told this is a cobalt blue Sulphide marble and that they are somewhat hard to find and most of them are just clear glass. There is a dog inside the marble and sadly it was played with a lot so it is a bit rough and hard to see the dog. It has a little nub where they broke it off when they made it and I was told not to have it polished or anything because that nub would disappear and that's bad. I would love to know where it's from and maybe what company made it and when! and I would like to get some opinions about having it polished or put in a kiln to smooth it out.