I agree, it looks like an Imperial.
Imperial was/is on the west coast that was a seller of many things including marbles from many countries overseas.
(A jobber)
To nail it down to which country it came from, would be very hard to do.
I am glad to see that you lit it hard--backlighting is even better.
Just take a small penlight, rest the marble on it--and shoot it---or just look at it--.
I just love this stuff.
Marble--On!!