This is interesting. Can you elaborate at all? For instance, when did this happen, how did this person get their hands on unsigned Matthews marbles, and what did they do with them?
It's a one color opaque game marble. Not many are worth a thing unless you're talking old handmades or transitionals. And it's usually very difficult to ID them, since most companies made them by the railcar full.
The one on the left gives me a pretty strong Vitro vibe. Is it veneered? To me, it sort of looks like it. As for the one on the right, I could easily see Master. Regardless, they're both very nice marbles!
Not sure I've heard the name - sounds cool though!
As for AV, some of the most common I think would be Royals and Moss Agates. I have seen it on Oxblood Patches too, and it wouldn't surprise me to find some on a Tricolor.