Thanks to everyone for your knowledge and feedback, as it's much appreciated! I believed the marbles to be Jackson, but a couple of other folks threw in options of Ravenswood and Cairo Novelty, so that's when I got lost in translation.😂 To further my ID investigation, these next 4 marbles are similar in that they have a deep purple hue, yet are opaque when backlit, the white swirls are thicker, but are not UV reactive, and measure between .59 - .62, so do y'all think they're also Jackson or...?🤔🔎 @cheese I'd really like to hear your expertise on these specific swirls, if you don't mind chiming in again, sir.😃