I dug the blue one up yesterday..
..out here in my Mojave Desert ghost town dump. And yes,my marble is unlike other colored game marbles in that it too has veins in it. Which makes me think it was'nt a game marble. I've dug up lots of old game marbles and each is solid color. Game marbles if they're red,black,white,blue,etc are solid color. If there's veins or swirls in them they're probably not game marbles. But they could be. I'm not the world's biggest expert on marbles.