Doesn't that depend on whether you are referring to singular or plural? Like if you mean one marble "Here's a marble for here is and Here're two marbles for Here are?
David McCullough made a lot of clear based swirly marbles while at Champion Agate.
in lots of different colors. Sorry I don't have time to post the clear based ones by themselves. I tried to pick out photos that included them.
I will add that the marbles they made are sure pretty. We even named one of them "Griff". I remember how proud they were of what they had discovered. I remember that more than I remember the marbles.