I don't have pics, but I have a couple of Pelt 7-Ups that have that very same dark emerald-green base. Like Mike said, they're among the more common marbles. But lovely all the same.
Technically -- according to Morphy's website -- Brian E. is not listed as one of the appraisers or subject-area specialists, but as Director of Promotions.
And look at the [Peltier] bubbles in that "green guinea" base.
This may be one of those instances when someone with a pretty narrow focus (CAC) tends to see what they expect, while others, knowledgeable in a larger arena, have a wider "comparison library" in their heads. In this case, their Pelt heads. But I'm pretty sure that even if I wern't a Pelt Head myself, the marble in question wouuld look like a Pelt MC swirl to me too. One I wouldn't mind having. But not at CAC prices! It'll be interesting to see how the bidding goes on it.