I never heard Ron refer to any Vitro as a "Sparkler" - maybe he was trying to start something, I really don't know. To me, it sounds like he might have just been trying to be funny. The sort of structure that marble shows is not exactly rare on Trilites and even some Conquerors, and I'd just consider them variants. Vitro never purposefully tried to make marbles like this, AFAIK, and it sounds like the moniker never really took, which is a good thing in my mind.