This is the only pic of it I have handy at the moment but I can take more tomorrow if it will help. It is an odd one sort of a brushed patch with yellow stripes.
I'm a little confused now Art. So Master Made didn't put their marbles in Master Made boxes but Master Glass did?
And I assure you, there are no Imperial Marbles in that group.
Of course, it's always tough to tell "original" with a box but I don't see anything that looks too out of place.
I'll be interested to hear what @akroorka says, though.
I think they're great, Joep, and given the look of them and the fact that they have been making marbles in the Netherlands for a very long time, my bet is they are quite old. How big are they?
Yeah, that's a great marble - they don't come much cleaner!
Nice group, Dave - lots of pink. It reminds me of a big collection I purchased from a woman around here who had collected for a long time - lots of pink and pastel colors on both hand-mades and machine-mades.
Pretty funny story, but since the interior looks threaded, I doubt it was a valve - some kid probably just stuck it in the fitting who knows when. It's definitely a cool Rainbo though, I think I'd be kinda glad for the mishap!