I just added some marbles to the popeye post to help make my point there. (:
The glow in marbles such as Realers (and some of the more modern marbles with fire inside) seems to come from the play of the light between the white and clear regions. I think the grain of the Realer is what gives it the glow, or the grain together with the type of white glass used.
Aces sometimes have conspicuous grain or striation, strengthening my hunch about what gives the marbles fire.
So when the glass batch had a whole lot of white, then that means less clear and less chance for the light to play around inside.
Here's Dani's Ace with hardly any white -- it made for a great pic:
Here's another of Dani's Aces with much more white and the glow was more subdued, though it still looks good and probably looked great in hand:
I have some marbles with the white base and black which I can see a soft orange glow through with strong backlight. I'm pretty positive those were from Ace runs.
And there could be ones you just can't see the light through -- but when I think about what run Akro made them in, I can't help thinking that it was more likely that they were made in an Ace run than in a Prize Name run.